Denon AVR-1601 5.1 Channels Reciever

I got this model from a friend who could not figure out the problem. Himself being somewhat of a electronics dude, I knew it was not going to be easy, but I did not figure it would be this hard to solve. I took the whole thing apart tonight, pulled out every board. I found one of the *ribbons?* had a bent pin, and fixed that up, hoping that was it, but also searched for more possibilities. finding nothing, I put it back together, but the same problems remains: It powers on, cycles through a few *DEMO-MODES?* and then goes into standby after receiver - a process taking roughly 5-6 seconds. Any help is graciously received, I can solder a little, but do not know any of the values of resisters, transmitters, or capacitors, though simple instructions such as "the "R-R-R-G" resister (red-red-red-gold) I can do.
Sincerely,
SORL.