Checked all fuses I could see they looked ok- I had unplug all three red/black connectors or 4400H won't start. I know it has a LOT of fuses so I'll try see if there's a specific one.What AVR? Check online to see if there is a fuse to replace. All amps dead sounds like a fuse to me. 1 amp dead or several dead might be board issues, but all dead usually doesn't happen. Most have short circuit protection these days.
It definitely leans more towards subs and diy kits here. Not as many passive crossover designers here as in some other forums but there is a few.Good then mine should be fine. suprised so little interaction on here. Guess AVS is all about Subs, GSG and DIYSG now.