Haven't tried to fly my Mavic Pro Titanium for about 7 months thanks to Covid lockdown.
I had barely had chance to take it out before covid hit. (Less than 10 batteries worth) It was perfectly fine last time I had it out.
Brought her out on the weekend to get footage of my cousins wedding. To my embarrassment in front of everyone I had been boasting about it to, I couldn't fly. The app was demanding an IMU calibration and wouldn't get past 1/5. I apologised to everyone and packed it up.
Back home, where I have a perfectly flat surface away from any steel or magnetic force. I have tried every trick and tip and youtube advice and still can't get past stage 1 of the calibration. After about 10 minutes of no movement on the progress bar I get an error-13 message ( I believe that means the drone got too hot)
Amongst attempts at IMU calibration I am randomly getting told to calibrate compass (which I can do with no problems).
I'm sure there is a fault but because of the Lock-down my warranty period is up.
Has anyone got any advise other than uninstall/reinstall app, try in a different location, different phone, different connection cable, start calibration with drone on it's side first, cold calibration or throw the friggin thing into the wall?   

Hello there Werribee Dave, thank you for reaching out and I am sorry to read and to know that you've encountered this kind of issue on your DJI Mavic pro. For us to be able to assist you further, may I have a screenshot or video showing error message and the response of the unit? In addition, what is the current firmware version of the DJI Mavic pro? Thank you.

Have you tried downgrading the firmware to the first version and then doing the re-calibration again to see if it makes it all the way through?

Then you can do a firmware upgrade to the latest version.

DJI Gamora Posted at 11-20 06:24
Hello there Werribee Dave, thank you for reaching out and I am sorry to read and to know that you've encountered this kind of issue on your DJI Mavic pro. For us to be able to assist you further, may I have a screenshot or video showing error message and the response of the unit? In addition, what is the current firmware version of the DJI Mavic pro? Thank you.

Thanks for getting back to me.
Running the latest version of the firmware. Took some photos with the missus' phone but thy have come out a big blurry and I'm away now.
first photo shows the progress bar stuck at about 95% of step1/5.
It stays like this until the error message appears.
Photo of the firmware numbers might be a bit unreadable sorry. Can try to get better one when I'm home if required.

Werribee Dave Posted at 11-20 15:04
Thanks for getting back to me.
Running the latest version of the firmware. Took some photos with the missus' phone but thy have come out a big blurry and I'm away now.
first photo shows the progress bar stuck at about 95% of step1/5.

Hi Werribee Dave, thank you for your reply and additional information, for us to clarify, during the calibration process, on the location where we set up the unit, was it in an area with the operating temperature range of 32° to 104° F (0° to 40° C)? please be advised that if the issue still persists upon multiple attempts of the calibration. I'm sorry to say that we will be needing to send in the DJI Mavic Pro drone back for a proper diagnosis and for us to know what is the root cause of the issue. For us to be able to assist you further with regards to this matter. Kindly contact our DJI Support Team at https://www.dji.com/support  Again, I am sorry for the trouble this has caused, and thank you.

Hi Dave,
did you col down the aircraft before you tried to calibrate the IMU? If not then you get the error message AC overheated. Cool it down in a fridge on 7°C then try once more the calibration. Note: Hold the AC dray if you cool it down!

Room temp would be around 18C - 20C.
Haven't put it in the fridge but have definitly let the drone cool to room temp.
The calibration process stalls and after about 5 mins I hear the fan in the drone kick in. Another few minutes later I get the overheat error message.

I see your Mavic´s cam is covered. Can you remove the cover and try it again in several minutes after removing the cover?

Peterx Posted at 11-23 04:54
I see your Mavic´s cam is covered. Can you remove the cover and try it again in several minutes after removing the cover?

Hi Peterx. Cam is covered only in these photos that I quickly took to show what is happening. All previous attempts have been with the cover off. Pretty sure there is a software issue. My DJI GO4 App thinks my drone is an Inspire 1. Will be sending it back to DJI as soon as they send me a lable. Thanks for your suggestions though.

Good luck that you get your copter as soon as possible.