Took delivery of the Mini 4 Pro around 3 days ago and, so far, Ive only managed to squeeze in a few flights due to less than perfect weather.
But Ive noticed 2 issues so far.
The first one relates to the IMU. Almost every time I power the drone up, it states 'IMU error' and asks me to calibrate it.........but then after about 15 or 20 seconds, it seems to rectify itself and Im able to fly. Ive had numerous DJI drones over the years and Ive never had this problem before. Anyone else getting this on power up?

The second issue raised itself earlier tonight and led to a minor crash. Due to a break in the weather, I went to a local firework display to capture some footage. The usual IMU error appeared then rectified itself, and the flight went as good as could be......except the actual firework display was running late.
Then, it suddenly started to rain. It was heavy...ish, but not torrential. Enough to warrant me bringing the drone down though.
So I hit RTH, watched it as it came back to me and then I cancelled the auto landing as, being dark and having taken off from a road surface devoid of any features, it was slightly off target and I decided to land it manually with a hand catch. Done this a thousand times before, never an issue.
However, as I put my hand out and the drone settled onto it, the motors didnt switch off as they usually do. I pulled the left stick down as this usually brings them to a stop.....but nothing. This was concerning as I was standing in pouring rain with a drone that I couldnt get to shut down and was trying to pull itself free of my grip. So as one would do in this situation, I decided to do an emergency shut down, and pushed both sticks down and out to left and right. The motors still didnt shut down. I tried again, then tried down and in towards the middle ....nothing. This went on for the best part of a minute, with the drone refusing to shut down or respond to the emergency stick shut down method. Eventually, due to my fingers becoming more wet due to the rain and the drone still trying to pull itself upwards and free of my grip, I let go.......at which point it decided to flip and dive down at an angle of about 45 degrees before smacking into the rear quarter of my car just above the wheel arch and landing on its back on the wet road surface. Both rear arms had folded shut in the process but there appeared to be no damage that I could see.
After getting it back home, wiping off the excess rainwater, which wasnt actually that much, I tested the arms, gimbal assembly and powered it up. Besides a few scuffs along the back edge of the top casing above the card slot and USB-c port, and another slight mark just behind the front right OA sensor, its all working fine. Thankfully.

The points here are one, why is the IMU giving a constant error message upon startup, before rectifying itself, and two, why did the motors refuse to shut down of their own accord upon landing, or despite several attempts to perform a stick emergency shut down?

I have one other thread on here which involved my previous drone, the Mini 3 Pro, which had a lengthy issue with the front left arm, which had gradually developed excessive free play in the axis mount to the point where it appeared ready to fall off. This was resolved however under the extended warranty. Prior to this however, Id had several exchanges due to the lens/camera housing fogging issue.

I was a bit dubious about buying Mini 4 Pro as its a lot of money to outlay for something which could turn out to have a few issues, as the 3 had had. That said, Id not seen any issues reported by those whove had theirs a few weeks, so I took the dive and bought one.
But this IMU error is a bit concerning, mainly in case it decides to appear during flight, and also the fact that the motors didnt shut down on a hand catch or emergency stick procedure.

Anyone else had these issues, or similar? Any input from DJI?

Cheers.

Hi there. Thank you for reaching out and we're deeply sorry for the incident that happened on the unit. I'm afraid that you may consider sending the unit in for a proper diagnosis. You may contact our support team to start up a ticket at https://www.dji.com/support . Also, the warranty can be applied depending on the outcome of the damage assessment including the warranty period of your unit. Thank you for your kind and understanding.

DJI Paladin Posted at 11-4 18:36
Hi there. Thank you for reaching out and we're deeply sorry for the incident that happened on the unit. I'm afraid that you may consider sending the unit in for a proper diagnosis. You may contact our support team to start up a ticket at https://www.dji.com/support . Also, the warranty can be applied depending on the outcome of the damage assessment including the warranty period of your unit. Thank you for your kind and understanding.

Thank you for getting back to me Paladin.
I probably will send it back in under warranty because Ive taken a look at the flight record on the RC-2 and I noticed that at the very end of the flight, where Ive attempted to land it on my hand, the altitude reading was actually showing as -5m, meaning the drones IMU believed it was some 5m below where it took off from. This would likely explain why the drone felt like it was trying to fly up, although it doesnt explain why it refused to shut down the motors.
To me, this does indicate a likely failure of the IMU during the flight, or at least the latter part of it.
The ground I was on was level, a road surface, and featureless, so I expected the vision sensors wouldnt give an accurate position when it came down to land, but the fact the drone refused to power down when I took hold of it or tried an emergency shut down, well, that is quite a concern.

As for the damage, its purely cosmetic, with a slight black scuff to the top casing, some minor black scuffs to the back edge of the top casing and also, which I noticed today upon closer inspection, a few scratches on both rear arm motors. Mechanically, its still solid, with no excessive play in the arms that I can tell.

Although I may return it in the very near future in relation to this incident, Ive taken steps to see if it was the IMU that was at fault. Ive refreshed the firmware today and, so far, its not asked for an IMU calibration. That said, this was indoors and not outside. If its okay with yourselves, Id like to keep it a few more days, a week maybe, in the hope that there will be a break in the weather and I can take it out for a test flight. Im looking to see if it asks for an IMU calibration outdoors, and how it performs during a daytime RTH, and also if it will power down upon landing on the ground, or a hand catch, or an emergency stick command. I did start the motors earlier and shut them down again with the stick command, and it worked as it should. I just want to satisfy my curiosity and see if the firmware refresh has resolved the IMU issue. I will still be looking to return it under the warranty purely because I look after my tech, especially my drones, and this one now has a few scuffs which Im not happy with.
Im just hoping that I dont end up going down the route with this M4P as I did with the M3P, where I had to exchange it several times due to the same issue which, in the case of the M3P was the lens fogging issue. I dont buy my tech to have to keep having it exchanged due to technical issues. I buy it to enjoy it, but to do that I have to have one that works as it should.
Just as a comparison, I had a Phantom 4 Pro from 2016 till earlier this year. Never had an issue with it in all those years. I clipped a few props on occasion when it toppled over on landing, but that was it. Ive had Mavics, a Tello, Mini 1 and 2 and even built and flew a number of F550s and F450s back in the day when they were all the rage.....never crashed one, or had any issues at all. With DJIs leaps with the tech in the Mini 3 however, I decided to register the purchase with yourselves and also buy the DJI Care Refresh package as I sensed that with such a big leap, there may be a few issues. I was right, there has been, and Im glad I did. Dont get me wrong. DJI dominates the market and quite rightly so, but I just felt a sense that boundaries may be being stretched a bit too much. That said, the 3 is a great drone and this, the 4, is everything the 3 should have been.........but thats DJIs clever marketing. Never give too much in one go and always have something at the ready, both to guarantee new high volume sales or knock the competition off its perch. Good strategy.

Thanks again.

Manich Posted at 11-5 18:04
Thank you for getting back to me Paladin.
I probably will send it back in under warranty because Ive taken a look at the flight record on the RC-2 and I noticed that at the very end of the flight, where Ive attempted to land it on my hand, the altitude reading was actually showing as -5m, meaning the drones IMU believed it was some 5m below where it took off from. This would likely explain why the drone felt like it was trying to fly up, although it doesnt explain why it refused to shut down the motors.
To me, this does indicate a likely failure of the IMU during the flight, or at least the latter part of it.

Thank you for your response, Manich. Rest assured that we will conduct some analysis on the unit once it arrives at our facility. We will also gather this feedback of yours and forward it to our relevant team. Thank you for your understanding and support.

DJI Paladin Posted at 11-7 03:04
Thank you for your response, Manich. Rest assured that we will conduct some analysis on the unit once it arrives at our facility. We will also gather this feedback of yours and forward it to our relevant team. Thank you for your understanding and support.

Hi Paladin
Not sure if youre still watching this thread, but Ive been able to fly the drone about 2 or 3 times since my last post thanks to the occasional day of better weather.
Im now considering sending it back for an exchange, the reason being Im still seeing errors with the IMU. On two of the flights its asked me to calibrate the IMU but then its cancelled this and went to normal behaviour ready for flight. What worries me here is if its telling me to calibrate the IMU then cancelling this, Im worried it could develop an issue whilst in flight. Going back to the 4th of November flight, following its refusal to power down the motors, when I looked at the actual path and flight metrics, when it was in my hand and refusing to power down, it was showing its height to be 5 or 6 metres lower than it was, which is very likely why it refused a shut down. Now there had been no warning or error messages throughout that flight, except a few wind warnings, and, like I said just now, it worries me that it could develop an issue whilst in flight and I wouldnt know. This could lead to any one of a number of problems.
Also, on two of these recent flights, I think there was an issue with the IMU because the Augmented Reality green flight line that appeared on the screen when I hit return to home actually showed the ground point in the middle of a field some 100-200 metres away, correcting the ground/landing position only in the last 100 or 50 metres from the actual take off point. Again this indicates its inaccuracy to some degree and, because the RTH function chooses the optimal route, it could mean that at some point it may choose an optimal route in which it begins to descend to a lower altitude some way off and actually come face to face with obstacles, such as trees, buildings etc. I know dense foliage or solid structures dont present much of an issue with obstacle avoidance, but if it were to begin to descend as it neared the take off point, its possible that it may encounter power or phone lines, which it would likely not detect, and that rightly concerns me.

Ive just powered up the controller and gone into the flight record for that flight. Ive taken a few shots of the screen with my phone at key points, those being when the drone is sitting on my hand and I have the left stick down to power the motors off, and several further shots of the sticks in manual shut down positions......and if you look at the altitude, it thinks its 5 or 6 metres below where it beleived it took off from. It was this that led to the crash because I couldnt shut it down and it was constantly pulling up, prompting me to release it at which point it flew into my car.
I'll post these in a following post shortly, after Ive got them on to my PC.

Cheers
Mike

Manich Posted at 11-29 16:31
[view_image]

As you can see from the time stamps and the stick positions, I attempted to shut the motors off for almost 40 seconds but it just wouldnt power down. You will also see the negative height as well.
The images might not be in order...apologies.
Regards
Mike

DJI Paladin Posted at 11-7 03:04
Thank you for your response, Manich. Rest assured that we will conduct some analysis on the unit once it arrives at our facility. We will also gather this feedback of yours and forward it to our relevant team. Thank you for your understanding and support.

Are you still following this Paladin?

Manich Posted at 12-1 01:53
Are you still following this Paladin?

Thank you for your response. This is not the experience we want you to have. Please continue with the process of sending back the unit so we can identify the main issues with this behavior. You may contact our team using the link above. We appreciate your understanding.