correction : the RC is a GL300AIf it didn't work when it was given to you, and you don't know why it didn't work in the first place, I wouldn't spend any more time trying to fix it yourself. Ship it off to DJI and let them diagnose it. Start the process at the DJI site. Try not to send them the controller as the GL200A is known for higher output. DJI cut the power back with the release of later models.