VSX-421 problem when powering from standby-mode

Hi, I have this reciever, I bought it faulty and replacing relays fixed all the problems but this one:
Reciever works normally until I turn it off/ put it in standby-mode and let it sit for some time. After that when I power it up it turns on but goes off in like 2 seconds. I have to reset it 1-3 times with enter+standby-button and after that it works again normally until I turn it off and let it sit for some time in standby-mode. I have not founded a schematic for this so it's difficult to troubleshoot. Inside it all looks really clean and no bulging capacitors or anything. When I press preset+standby, it gives only these: DC: 039, temp1: 00, temp2: 00, Over: 255. I have no idea what these mean :D How would you proceed to troubleshoot and can anyone tell me where to find the schematic for this model? Thanks!