Are you getting DC power on to the actual amplifier board?
eg. Can you check the voltage between pins 4 & 8 on one of the 4558 dual opamp ICs??
And can you post better photos - a large part of the PCB is in shadow & nothing legible.
There will ne another PCB or block for the AC input & power supply somewhere in the thing; it could be that it has power, but nothing beyond that. Testing power on the amp board ICs is a good starting point.
[I had a creative 5.1 surround system for a while; it was a terrible design and I ended up scrapping it and using the speakers with a homemade amp setup].