I have a 3605 Enterasys AP installed, which uses a wireless controller. The AP was working, but now the controller says its Radios are OFF. However the AP still has an address, and the controller shows it as up. Does this mean the AP isn't getting enough power, or something else?
If you use DHCP for the APs you'd also try to just delete the AP from the controller database.
I've seen some cases were the config wasn't synced to the AP.
The 5 GHz radio could be disable if DFS is enabled and a radar is detect. But i think this should be seen in ap log. Have you looked what the ap log output says?