UPDATE. ANOTHER POSSIBLE SOLUTION:
if you are using the app to update and updated your RC first and now have signal lost. Make sure you have WiFi service and have the app, RC, and aircraft powered up and when the aircraft status says aircraft requires up, download and install and then follow the instruction and after downloaded hardwire the device to the aircraft with the USB OTG cable and see if it will let you upload the firmware to the aircraft. I tired and it failed because alfter unplugging the USB from the RC to pklug it into the aircraft I turned off the RC.
When I powered up the RC, it was able to finish the uploading firmware to the aircraft.
SO, LEAVE THE RC POWERED ON DURING THE ENTIRE AIRCRAFT UPDATE PROCESS.

For this round of firmware since the RC needs to match the aircraft firmware, updating the RC first may not let the aircraft update.
For those who are having trouble with the firmware update on your P4 and getting RC Signal Lost it means that you do not have the update done on both the Aircraft (1.1.301) and RC (1.6). This means you probalbly updated the RC first, If the aircraft will not take the update, you can update the aircraft through the Assistant2 PC or Mac program.
OR, downgrade the 1.6 RC firmware to 1.5.8. To do this, from the home page upper right corner is a graduation hat icon. That takes you into the Academy section of the app when you press it.

Have the RC on connected to the app and the aircraft OFF.
DO NOT give it a quick press, instead keep it pressed down for 5 seconds or so and let go. Then you will see the RC firmware downgrade to 1.5.8 page.

This should take care of the update, and it takes a wile to update the aircraft firmware. When you power up everything it may take several minutes for the "Aircraft Requires Update" message to show in the Aircraft Status page.
ALSO, YOU CAN UPDATE THE AIRCRAFT WITH THE ASSISTANT2 SOFTWARE.
If you do, the progress bar may stop after several minutes BUT if you hear the P4 power cycling tones/beeps then it means it's probably updated. Leave it for at least 15 minutes to see if the progess bar completes. If not, close the Assistant2 program, then power cycle the P4 and restart the Assistant software and see if the P4 is updated.
You can also verify by powering up the RC, app, and USB cable and then see if the RC Signal Lost is gone.

Please post if this has worked for you or not.

I used the DJI Go app on iOS to update. It never downloaded the craft update, only the RC update. Thus, I received the dreaded RC Signal Lost error. I tried update the craft firmware via Assistant 2 on both Mac and Windows. Both downloaded the update, but then failed during install. I tried this multiple times. I then downgraded the RC firmware.

This morning, I tried to first update the craft firmware using Assistant 2. Again,it downloads the update, but nothing but failure during install.

The craft update is NOT available in the DJI Go app this morning, yet the RC update is.

What is wrong with my DJI drone?

zavoodi Posted at 2016-4-10 00:15
I used the DJI Go app on iOS to update. It never downloaded the craft update, only the RC update. Th ...

You downgraded the RC to 1.5.8 ?
If so, then power everything on and wait several minutes and you should get the "Aircraft Requires Update" in the overall status.
Also, go to the About page in the General Settings and see what the aircraft firmware says.

Just bought a P4 from Best Buy. Things were fine until I did the firmware update. Now All I get is Sinal Lost. Camera works but I can not operate anything else. On the about page is App: 2.2.7. Ver. 01.01.0301.  RC N/A

How do I resolve this issue... Or do I take it back to Best Buy for a refund.

DJI needs to make an easy fix for this, write a routine where you can plug into the controller and the Phantom and write the correct software or quit having the app tell us to update if it's going to screw it up.

If the aircraft is off, how is the app supposed to connect, please post steps, do we need to use the cables? If the remote can't communicate  with the aircraft then how is it supposed to do it?

zavoodi Posted at 2016-4-9 12:15
I used the DJI Go app on iOS to update. It never downloaded the craft update, only the RC update. Th ...

Exact same issue and scenario for me this morning. I had important work to do with drone TODAY and now a $1400 item is useless because of some dope not explaining to customers how to and how not to update the firmware.

These two attachments are completely worthless.

DJI Ken, If you're gonna try to help us, then post exact instructions, turn what off? What button on what, just don't assume we got the same training you got working for the company, we all are pretty pissed off that the system tells us on the screen that we need to upgrade something and when we do it, we find out that we didn't do it in the right order, I too needed to take some video of a once in a year event which didn't happen because of this screwup by your company, when you put a big RED warning on our screen before we take off that an upgrade is needed and we do it, it shouldn't BRICK THE DAMN THING

Thanks DJI-Ken  - the procedure worked for me and got my bird back in the air.

RTDudash Posted at 2016-4-10 01:09
Just bought a P4 from Best Buy. Things were fine until I did the firmware update. Now All I get is S ...

Power everything up and go to the About page in General Settings and what does it say for the RC, can you post a screen shot.
When everything powered on what color is the left LED on the RC ?

nrechtman Posted at 2016-4-10 02:01
DJI needs to make an easy fix for this, write a routine where you can plug into the controller and t ...

I am sorry you are experiencing this, it will get resolved soon.

nrechtman Posted at 2016-4-10 02:31
If the aircraft is off, how is the app supposed to connect, please post steps, do we need to use the ...

I am only talking about having the aircraft OFF if you cannot update and the RC is updated but the aircraft will not.

porscheboxtersp Posted at 2016-4-10 04:39
These two attachments are completely worthless.

They are not worthless and lots of people have completed the firmware update from following the instructions I've posted.
PLEASE READ THEM AGAIN, this was a fix ONLY if you updated the RC first and now it will not update the aircraft. Post some screen shots and I can help you to update.

nrechtman Posted at 2016-4-10 05:31
DJI Ken, If you're gonna try to help us, then post exact instructions, turn what off? What button on ...

I don't see how much simpler I could have explained it.
Again, I posted a fix only if you had issues updating and updated the RC first and now the aircraft will not update.
So basically, if that's what you did then follow my instructions and get the RC back to 1.5.8 then power everything on and just wait for up to 10 minutes (WiFi connected) and you will eventually see that "Aircraft Requires Update" in the overall Status page. Then update the aircraft first before the RC.

nrechtman Posted at 2016-4-10 05:31
DJI Ken, If you're gonna try to help us, then post exact instructions, turn what off? What button on ...

And I did not get training in this fix. I too tried updating a P4 and I figured this fix out on my own and started sharing it to users to see if it helps them.
It may or may not help, but it got the P4 I was trying to update to work.

Please post if downgrading the RC to 1.5.8 then starting over and updating the aircraft first, then the RC is solving the RC Signal Lost issue for you.

Ken, your solutions worked for me.  After powering both up i got firmware updates required for both the A/C and RC.  Just so happens the A/C came up first.  Wish i would've got this the first time.  I plan to hold off a while before updating either of them.  Thanks for your assistance.

ok well. my rc is on and connected to wifi on ipad. p4 is off now. after clicking right upper cornet graduation icon there is no rc downgrade page. just 1)flight simulator 2) video tutorials 3) flight tutorials and user manuals.. thats all..

mdhall0290@gmai Posted at 2016-4-14 04:58
Ken, your solutions worked for me.  After powering both up i got firmware updates required for both  ...

Glad you are up and running

csivet Posted at 2016-4-14 05:29
ok well. my rc is on and connected to wifi on ipad. p4 is off now. after clicking right upper cornet ...

You need to press the icon down for 5 seconds or so.
You can just update the aircraft in the Assistant2 software.
http://www.dji.com/product/phantom-4/info#downloads

For me the RC downgrade is not available anymore from the Academy page. If the same for you just update the aircraft from your computer.

yeah i'm holding 5 sec even 10 secs but nothing happens.. after trying on 2 different mac, dji assistant 2 is not working too. now p4 is useless..

csivet Posted at 2016-4-14 06:39
yeah i'm holding 5 sec even 10 secs but nothing happens.. after trying on 2 different mac, dji assis ...

Can you post a screenshot of the overall status and about page?
Turn off the aircraft, have the RC powered on and connected to the app with the USB cable. Then press the graduation hat icon for 5-10 seconds. It will take you to the RC downgrade page.
If you still cannot do it, then please post a video with your cell phone showing that pressing the button does not work for you.

DJI-Ken Posted at 2016-4-13 21:30
Can you post a screenshot of the overall status and about page?
Turn off the aircraft, have the RC ...

Hi,

I had the same situation but when I click to DOWNGRADE it doesn't even show previous firmware. It

spam1@epaymentn Posted at 2016-4-29 13:53
Hi,

I had the same situation but when I click to DOWNGRADE it doesn't even show previous firmware ...

I had the same situation but when I click to DOWNGRADE it doesn't even show previous firmware ...
It says NONE in the firmware field for the RC????

I deleted the appp and reinstalled and now doesn't even show the DOWNLOAD button to download the firmware.

Thx

spam1@epaymentn Posted at 2016-4-30 01:54
says NONE in the firmware field for the RC????

If you more the sticks to the CSC position an you have the aircraft off while in that screen correct ?

spam1@epaymentn Posted at 2016-4-30 01:53
Hi,

I had the same situation but when I click to DOWNGRADE it doesn't even show previous firmware ...

If it doesn't show previous firmware than you may already be on the lower 1.5.8 firmwareThis thread was for RC signal lost and the only way you will get that on the P4 is if the RC is not on the same firmware as the aircraft.
RC 1.5.8 matches aircraft 0288, and RC 1.6 matches aircraft 301

DJI-Ken Posted at 2016-4-29 13:59
If it doesn't show previous firmware than you may already be on the lower 1.5.8 firmwareThis thread ...

It upgraded the the RC before the aircraft.

It says:
PRODUCT: UNKNOWN
CURRENT VERSION : UNKNOWN
SELECT VERSION FIRMWARE: NONE.

Thx

spam1@epaymentn Posted at 2016-4-29 14:08
It upgraded the the RC before the aircraft.

It says:

when I click about:

APP: 2.8.0
AIRCRAFT: 01.00.0288
RC: VERSION UNKNOWN
FLIGHT CONTROLLER SERIAL NUMBER:  N/A

spam1@epaymentn Posted at 2016-4-30 02:10
when I click about:

APP: 2.8.0

Can you update the aircraft via Assistant2 software on your PC/Mac?

DJI-Ken Posted at 2016-4-29 14:24
Can you update the aircraft via Assistant2 software on your PC/Mac?

I did download the Ass2 but when the main page opens it show the image to plug the USB in the computer when I plug the USB it keep showing that I need to plug the USb. It seems that it did not recognize the connection BUT my computer is showing that the aircraft is connected and I see the DCIM sub directory.

Another thing, there are some ERROR CODES showing on the same screen in the background.

spam1@epaymentn Posted at 2016-4-30 02:29
I did download the Ass2 but when the main page opens it show the image to plug the USB in the comp ...

And the drivers are installed correct?
You have the RC OFF right ?And if you power everything up, in the app what does it show in the About page. Can you post a screen shot. This is when not connected to your comuter.

DJI-Ken Posted at 2016-4-29 14:31
And the drivers are installed correct?
You have the RC OFF right ?And if you power everything up, i ...

Are we talking about the PC or the IPAD app?

spam1@epaymentn Posted at 2016-4-29 14:52
Are we talking about the PC or the IPAD app?

Sorry the IPHONE FLIPPED THE IMAGES

spam1@epaymentn Posted at 2016-4-29 15:07
Sorry the IPHONE FLIPPED THE IMAGES

Can we manually upgrade using a memory card like with the P3.

I really need to get this thing up and running I have a wedding in few hours and it will cost me more $3000.00

Thx again

spam1@epaymentn Posted at 2016-4-29 15:10
Can we manually upgrade using a memory card like with the P3.

I really need to get this thing up  ...

Picture from the IPAD APP and Assistant 2

Ken,

Any news yet???

Thx

Try this mate....

spam1@epaymentn Posted at 2016-4-30 03:10
Can we manually upgrade using a memory card like with the P3.

I really need to get this thing up  ...

No you cannot manually upgrade with a BIN file. It has to be done on the phone/tablet or PC/Mac.

spam1@epaymentn Posted at 2016-4-30 03:16
Picture from the IPAD APP and Assistant 2

You should only use that menu (graduation hat 5-10 seconds) for the RC downgrading.