Do you have a trigger hooked up? If so make sure your settings haven't accidently been switched from remote to manual. Even if you do use a trigger it might not be a bad idea to switch it over to manual and try turning it on that way, just to give both ways a try. I use remote power triggers and when the power goes out from a storm when the gear is in use the amps don't come back on on their own when I power everything up again. I always have to press the front power switches to get them to fire up that initial time.
