Niles SW6.5 - SW6.5 stopped working while I was on vacation. Need schematic to tro

I’m new to electronics, but have a general idea of how to troubleshoot the basics. I am trying to find a schematic to further my chances in finding the cause of this failure.
While on vacation, I believe there was an overcharge in the home electrical system. When I returned home, my TV, receiver, and this sub had all been damaged. TV was fixed by charging the board. But I would like to fix this by finding the problem components.

I have tried testing for continuity and even trying to find how far the power flows, but doing it blindly and with little knowledge of electronic repair is next to impossible I think. I need some advice. Any help will be greatly appreciated.

The original diagram is not provided by the manufacturer. But this is a typical design, not different from this type of solutions. Post photos of the interior, key elements, and you will certainly be able to choose a scheme of similar solutions.