The power supplies are divided up into sections. I would bet that there is no power to the power amp boards.
I should amplify my answer. Whilst there is one power transformer, it has different voltage taps going to different power supply boards. Everything that is working is low voltage, typically 5 volt or +/- 5 volt.
The power amp boards on the other hand for a receiver like that will need voltages in the 80 to 100 volt range.
In addition power supply boards to class D switching amps are complex because of the high switching frequencies.
This case highlights that we do need right to repair legislation. Circuits, let alone service manuals are never made available to you or me, let alone the local repair guy, if any are now left. I'm not even certain service manuals exist. With surface mounting of components boards are pretty much non repairable. I suspect it is identify the board and replace at the factory service centers..
Slipper has a good thought about the relays. These operate via LM IC timer ICs. I think these are generally on the amp board, but I can't be certain. If the relays click that might be evidence there is still power to the board. However that would be a low voltage operation and so likely is powered from a different power supply board than the amps, at least the power end. The power amp board will have low voltages to the voltage gain ICs and high voltage to the power switching MOSFETS. So no definite conclusion can be drawn as to cause whether the relays click or not.
Without at least a circuit everything anybody says will have a high degree of guess work involved.
The bottom line is that you can throw the dice with a trip to the factory repair center, or recycle. The problem with the former is that so much of the cost will involve finding the problem. You will have to pay for that and quite likely find out the unit is not worth the expense of repair. Unfortunately this means accelerated replacement cycles for units like receivers.
