After transferring files to PC (via USB), I switched off OA4  and disconnected the OA4 from PC. Let it on shelf for more than 3 hours. Then  when I took it in my hands it was super hot. I switch it on to check battery: it was at 25% whereas it must have been near 90% after file transfer.
Doing a switch on and off stops the heating and battery drain...

This is something I had already experienced a couple of times with my first version of OA4.

That is indeed strange especially that you had the same problem on your first OA4. I did not experienced this on mine, other than the burn in of the green usb icon on the LCD if file transfer is longer than 10min. And it took approx2/3 hours for the burned in after image to go away which I think they have fixed by dimming the lcd when connected in the latest firmware. Hope other can help you, as you have experienced this on your first OA4 there might be something more than just trying to switch the battery and see if it happens since you have switched it off and auto turn-off is max 30min.

Hi, Yaman-Python. Thank you for reaching out. Can you please try to fully charge the camera and then turn it off again to see if the issue persists? Please keep us posted. Thank you.

DJI Gamora Posted at 8-26 02:47
Hi, Yaman-Python. Thank you for reaching out. Can you please try to fully charge the camera and then turn it off again to see if the issue persists? Please keep us posted. Thank you.

Hi Gamora, Thank you for looking into this.
Today, I did a long timelapse where OA4 was connected to a powerbank and was fully charged when I stopped the timelapse. I transferred files to PC and there was no heating/battery draining problem that time and the battery was at 100% before and after file transfer.
Later I took various photos, videos and another timelapse without powerbank attached. After I transferred files to PC, the same heating/battery draining as I described in first post happened. Again turning on/off the cam stopped the heating. After that, for test purpose I took a few shots and transferred files again, or just connected to PC in transfer mode  for a while, but the problem did not happen again today.
So I can try to fully charge the battery as you said, though I think the first thing I did today (with the powerbank) would be equivalent. Anyway, I will keep you posted if there is some progress.

Update for today:
Today, I did again a long timelapse (~2.5 h: 4K, Video+pics; 4s) starting from 100% battery. After that the battery was ~80%. Then I watched the timelapse on the cam one time, then transferred all files to PC via USB, switched-off, disconnected USB. I noticed the cam was quite hot at this point. But it did not cool down. The same continuous heating/battery draining happened. Even I tried to cool it a little with my hands (heat transfer from cam to hands!) just a few seconds, it would heat again. After ~ 20-30 min, I switched on the cam and it was at ~30%, showing the battery drained continuously. Again, turning on/off the cam stopped the heating.
I then erased the files from cam, recharged battery (not fully this time), did a couple of videos, one pic, and later another long timelapse, and then again the same problem happened after transferring files to PC.
It might be related to how hot the cam gets at the end of the file transfer, which would be consistent with the fact that it seems to happen when a lot of stuff is transferred to PC...

You said this didn’t happen with the powerbank. So maybe the battery is defective. You don't have another DJI battery to test it with?

osmonauta Posted at 8-27 07:35
You said this didn’t happen with the powerbank. So maybe the battery is defective. You don't have another DJI battery to test it with?

Could be. But even without the powerbank the problem does not appear in most cases. It was the first and only time I used the powerbank. I am more thinking about an overheating during transfer which could do something to the cam/battery. I will try to test that later.

DJI Gamora Posted at 8-26 02:47
Hi, Yaman-Python. Thank you for reaching out. Can you please try to fully charge the camera and then turn it off again to see if the issue persists? Please keep us posted. Thank you.

Update: I tried that but it continues. It does not happen when I transfer just a few files, but it happens almost systematically when lots of data is transferred in one time. Like the other day, I transferred ~ 25 Gb and it happened.
Today I did a timelapse, transferred 3.6 Gb and it is happening. The room is at ~ 31C according to my watch which is not on my wrist. I took a magnet that has a cheap thermometer on it and put it on the OA4. It was originally at ~32 C (before setting it on OA4). It is now >40 C (42 C I would say from the photo attached). Been hot since I stopped the OA4 after transfer, and for ~ 1h. I stop it now by doing a switch on/off. Battery is at 50%. did not check battery after timelapse but it was full before it, and usually, such a timelapse decreases battery by less than 20%. OA4 now stops heating, as  usual.

Check if it is the camera or battery producing the heat by pulling the battery when it happens. Also check if the battery is "swollen" or bulging.

stagnant Posted at 8-31 04:52
Check if it is the camera or battery producing the heat by pulling the battery when it happens. Also check if the battery is "swollen" or bulging.

I had a look at the battery already a couple of times, and now, it looks fine.
The cam heats in a usual manner I think, that is, the display and lens (the heat sinks) are the hottest parts, like during normal use.
I could try to do what you say. But not sure if it could be conclusive. The cam and battey will be hot. Maybe battery more than the cam, but it could also be in normal use...

The heat would try to escape through the camera even if it is the battery that is the culprit.  I have had this happen not with a camera but a flashlight once where the batteries got stuck in a state of high drain even if the light was not on so thats why i figured it was a good idea to test it. Hope your problem will be resolved no matter what the problem turns out to be though.

stagnant Posted at 8-31 05:10
The heat would try to escape through the camera even if it is the battery that is the culprit.  I have had this happen not with a camera but a flashlight once where the batteries got stuck in a state of high drain even if the light was not on so thats why i figured it was a good idea to test it. Hope your problem will be resolved no matter what the problem turns out to be though.

OK, thanks for the tip. I will look at the battery next time.

I believe you mentioned in another thread that you sold your OA3? If you know anyone with another unit (either 3 or 4) would be interesting to repeat the process using your battery. If their unit will also produce the same issue, then it must be the battery. Otherwise the unit must be bad.

osmonauta Posted at 8-31 11:02
I believe you mentioned in another thread that you sold your OA3? If you know anyone with another unit (either 3 or 4) would be interesting to repeat the process using your battery. If their unit will also produce the same issue, then it must be the battery. Otherwise the unit must be bad.

Indeed. But no other battery in sight.
In any case, unit or battery, it looks like I am the only one with the problem, so l have to think about contacting DJI about it. The fact that it happened with my first unit too let me think it could be a more common problem or that they sent me back the same unit (which I doubt).
If they have some info, they could let me know here.  I will do some additional tests over the weekend and will take a decision.

stagnant Posted at 8-31 05:10
The heat would try to escape through the camera even if it is the battery that is the culprit.  I have had this happen not with a camera but a flashlight once where the batteries got stuck in a state of high drain even if the light was not on so thats why i figured it was a good idea to test it. Hope your problem will be resolved no matter what the problem turns out to be though.

It happened again today. After one hour, I took the battery out. It was at the same temperature (judging by touching with hands) as the rest of the camera, so I do not think it is battery problem.

Experiment to test influence of battery: Took a long timelapse just to get lots of stuff in the cam. Removed the battery. Connected cam to PC via USB. transferred all the files (took a few minutes). Once done, switched off the cam and let it connected to PC by USB. After 1 hour, the cam is still and remains hot. I switch on/off the cam, still connected to PC, and it stops heating.

==> not a battery problem. ==> In these particular circumstances, the cam dissipates heat even it is off.
Dear DJI, any comment at this point?
  

Try different usb-cable.
When I had gopro I never knew when it was charging or not, and those times it was not charging it got really hot. Switched to better cable and it solved the problem.

Just worth a try.

johansenfoto Posted at 9-1 00:00
Try different usb-cable.
When I had gopro I never knew when it was charging or not, and those times it was not charging it got really hot. Switched to better cable and it solved the problem.

Thanks for the tip. It happened  in different locations, with different PCs, and different USB cables, even cables I use to charge without problemOA4 and other things. There is no problem when charging in fact. It is only in these particular circumstances. Will try another cable anyway next time.

Yaman-Python Posted at 8-31 22:43
Experiment to test influence of battery: Took a long timelapse just to get lots of stuff in the cam. Removed the battery. Connected cam to PC via USB. transferred all the files (took a few minutes). Once done, switched off the cam and let it connected to PC by USB. After 1 hour, the cam is still and remains hot. I switch on/off the cam, still connected to PC, and it stops heating.

==> not a battery problem. ==> In these particular circumstances, the cam dissipates heat even it is off.

Hi, Yaman-Python. Thank you for the update. Upon consultation with our relevant team, since the issue happens randomly, it is much better to send it to our facility for proper diagnosis.  You may submit an online repair request through this link: {https://repair.dji.com/repair/index}. If you need assistance with creating a ticket, you may contact DJI support at (https://www.dji.com/support). We understand that this is not the answer that you look forward to, but this would be the best thing to do in this situation. In addition, warranty service can be claimed depending on the result of the Damage Assessment. Your kind understanding is appreciated and thank you for your continued support.

Hi Gamora, Thank you for the response. I will follow your advice, unless you have another more straightforward solution after seeing my additional comments below, from my experience today.
It is not random. It happens systematically when a lot of data are transferred.
My experience today below:
Today I did a long walk and, staring with full battery, took for ~ 20Gb of videos (4K60) and a few photos. Battery was at ~20% before connecting to PC for transfer. It happened again (transfer to PC finished; switched off; remove USB cable): it remained very hot for over an hour. Then it finally started to cool down. I switched on the cam but it would not (3 red led flash). The battery was fully discharged during the heating period. I connected the OA4 to powerbank, switched on, and indeed the OA4 said battery low.
When a lot of stuff is transferred to PC via USB, it happens systematically. It cannot be a normal behavior.

DJI Gamora Posted at 9-2 04:24
Hi, Yaman-Python. Thank you for the update. Upon consultation with our relevant team, since the issue happens randomly, it is much better to send it to our facility for proper diagnosis.  You may submit an online repair request through this link: {https://repair.dji.com/repair/index}. If you need assistance with creating a ticket, you may contact DJI support at (https://www.dji.com/support). We understand that this is not the answer that you look forward to, but this would be the best thing to do in this situation. In addition, warranty service can be claimed depending on the result of the Damage Assessment. Your kind understanding is appreciated and thank you for your continued support.

Hi Gamora, Thank you for the response. I will follow your advice, unless you have another more straightforward solution after seeing my additional comments below, from my experience today.
It is not random. It happens systematically when a lot of data are transferred.
My experience today below:
Today I did a long walk and, staring with full battery, took for ~ 20Gb of videos (4K60) and a few photos. Battery was at ~20% before connecting to PC for transfer. It happened again (transfer to PC finished; switched off; remove USB cable): it remained very hot for over an hour. Then it finally started to cool down. I switched on the cam but it would not (3 red led flash). The battery was fully discharged during the heating period. I connected the OA4 to powerbank, switched on, and indeed the OA4 said battery low.
When a lot of stuff is transferred to PC via USB, it happens systematically. It cannot be a normal behavior.

just out of courosity can you  take any  devices taht may trigger the Bluetooth away, close down the DJI mimo app, and if you are on 2.4ghz, switch to 5ghz,   how bout trying a different cable and  possible another computer. if this still persists maybe its time to send in the camera for  a new one then  try to coninue to figure out a  issue  Just offering some suggestions

Fishycomics Posted at 9-2 05:46
just out of courosity can you  take any  devices taht may trigger the Bluetooth away, close down the DJI mimo app, and if you are on 2.4ghz, switch to 5ghz,   how bout trying a different cable and  possible another computer. if this still persists maybe its time to send in the camera for  a new one then  try to coninue to figure out a  issue  Just offering some suggestions

Hi, Thanks for the interest.
Already tried different PCs, usb cables, even 2 different SD cards (Kingston and Sandisk).
As for wireless connections, I have not touched these at all. The only time I connected to mino app was for registration. and mimo app is not opened.
I am on 2.4GHz, and otherwise there is 4.8 GHz in the menu but it not allowed. Stuck on 2.4 GHz.
Only my PC has a bluetooth on, my phone is usually off except when I need it. I could try to switch it off during the transfer, though it has not notified me of OA4 trying to sneak in (especially the OA4 is off when it is heating and consuming battery). But any I can try to switch off PC bluetooth.

About randomness: if it is, I should buy lottery tickets, because I am always wining recently!
I recharged the battery. re-transferred the same files (~20Gb) to PC, etc., and now OA4 is heating again!
And I had stopped wifi and bluetooth during the transfer just in case.
Anyway, I have started the "repair request". Will probably send the thing tomorrow.

I would just take the memory card out and use a card reader, would solve the problem with heating.

  agree if the card is  the card  very big is gb size ot a standar d64gb

johansenfoto Posted at 9-2 08:26
I would just take the memory card out and use a card reader, would solve the problem with heating.

Hi Johan&Fish,
Well, I already know a workaround: switching on and off stops the heating, so I could just switch on and off after transfer and that's it. I used that workaround actually.
But I am uncomfortable having a camera that behaves like I have described. It is certainly not a "feature". And with all these reports of burning batteries, I am not comfortable having a camera heating up when it should not.
FYI, I used 64 Gb SDs.
Anyway, I am curious of what DJI will find and answer.
Randomness assessment: This morning I transferred again the same data to PC, and it happens again. 3/3 win so far. but I will stop the winning streak here. Will send theOA4 today I think.

Good decision!

Could not resist doing it again, but with another PC! Won again: 4/4. All PCs tested were windows 10.
DJI, just in case it does not show up with a Mac PC, try Windows.
Camera is now in box, will be on its way soon.

johansenfoto Posted at 9-2 08:26
I would just take the memory card out and use a card reader, would solve the problem with heating.

I always use card reader. Don't understand why SD cards seems to be harder to remove from the device. If camera is directly connected to the USB-C it requires camera to handle the sharing process and mount the SD card. And if you force remove it it may lead to software errors by the camera.

Anyways SD cards should be easier to remove from the device just to change the card that is full.

Got the OA4 back.
The positive: Process was fast. Checking was done in 2 days. They did not charge me for the inspection.
The disappointing: They replied the OA4 works according to specifications. Plus a long explanation on why it is normal that OA4 heats up during operation (not really what I was complaining about in fact).
They received the OA4 in the morning and I got the result in the evening by email. I replied it was a pity they could not reproduce what I had described (I asked them to look at this thread but doubt they did. I also doubt there was any communication between them and the DJI people dealing with this forum. They did not refer to it in their responses), but that it could not be helped. Next day they replied they would do a second check, which was again good and they sent the OA4 back to me.
Now I tried again on my usual PC and it did it again: 5/5. Then I tried 2 times with an old PC running Windows 8, and it did it 1/2. So not 100%. Then I did it again with my PC and recorded the whole process (no interruption; This time I did only 30 min after switching off) and it happened again. See video below.
So this is the conclusion: at least my unit of OA4 has a hand warmer function that can be activated by the way I described, but it does not always work. Again it does not happen for a small amount of file transfer (may have to do with how hot the OA4 gets during long transfer). Anyway I know how to prevent it from happening: on/off after transfer.