Code 40021: Gimbal IMU data error. From the DJI error book It basically means it is an error internal to the board ( the drone cant see it) DJI's answer for this is ..Replace component. If you are certain that the cables are seated firmly on the board and you cannot calibrate without getting errors or it just wont do it ...Replace the unit. 30050 is the calibration needed notice and 30047 is the Barometer ( that will show with other errors)
Replace a defective or broken IMU module. Compatible with either the
Mavic Air 2 or the
Air 2S.
www.ebay.com
Sorry BUT the 400
12 error is a bad gimble board.
Code 40012: Gimbal unable to connect. Repairs required. Contact DJI
Support for assistance. Need to replace the gimbal.