I think you can edit the title; not sure though.
Power amplifiers tend to have a lot of interdependent parts, so one component can blow several others. This makes troubleshooting/repair sometimes difficult.
I suggest opening it and looking for blown fuses. If it works after replacing, fine. If not, it's probably time to look for another hand me down. If you really want to go further, then look on the net for a schematic (about $25). I see on the net that the amplifier seems to be worth about € 140.