Posting my experience here since its somwhat relevant. I had a mavic air that i wanted to sell, so i sent it to my local DJI repair center for a check. That way i could get written proof for the potential buyer that my drone was issue free. Btw, never had any problems with my drone. Well, after a day, the tech calls me and says that everything loooks good, but he cannot get the assistant 2 to callibrate the drone. He tried several things, and he also tried 2 more mavic air in the shop for comparison that had no issue calibrating. So he could not sign off on the condition of the drone. I took it home, connected to my pc and the drone calibrated without an issue. Called the DJI repair center and explained that i had used the original USB cable that came with the drone. He apologised but could not understand why he could not get it to calibrate himself after having tried multiple cables and pc.