My controller wouldn't update when connected to my iPad with DJIGO... so I tried plugging the controller into my IPhone with DJIGO instead, and that worked
Fixed my problem. Do you have 2 deviced with the DJI Go App? Like an ipad and an iphone? If so try the update with another device. I switched from my ipad to the iphone, and the update came up to download right away
Having the same problem with my Inspire 1 controller. Just downloaded the new firmware. The aircraft and batteries updated just fine, but the controller won't update with the app or the usb stick. I have the same mesasge on the ipad 'RC Signal Lost'