Getting error 71 when attempting to calibrate IMU.. Suggestions ?

Hi, there. Thank you for your query to us and we do apologize for the inconvenience. Can you please try to calibrate your Mavic at a low temperature and reboot it after calibration, Then check if it is ok. You may try it multiple times.  Also, may I ask if the Aircraft suffer a crashed or hard landing prior to the issue showing in your DJI Go 4 app? If yes, We highly recommend you to contact our support team to start up a ticket. We have the professional team who would do their best to find out the reason for the issue and then the corresponding resolution would be provided. Please note that DJI will not perform data analysis for cases occurring after the expiry of the warranty period; otherwise, valid charges will apply. Please keep us posted on the latest updates for us to further help you with this concern. Thank you for your kind and understanding. Best Regards.

Sorry to hear you have this problem. I had the error once and after some research it was suggested to hit the drone a little on the side. Got the idea HERE

Most of what I read had to do with the Spark.
Hope you get your problem resolved.