There was no problem with my DJI MAVIC AIR, but DJI GO 4 evers said, UPDATE FIRMWARE, so I did.
After the update, it shows me EROOR: MAINCOTROLLER, I have to restart and calibrate all sensors, but I cant....
So what should this be?
There was no fallen down or something else.

Hello there bockele. I am sorry for the inconvenience and thank you for reaching out. Can you please try to restore the settings to factory defaults and flash the firmware using DJI Assistant 2. You can download the software here: https://www.dji.com/it-en/mavic-air/info#downloads and follow the video tutorial below. Please let me know if the issue persists. Thanks for your support.