Testing/Repairing an Amp

I got an amp off of my cousin that stopped working after it got wet (not soaked but enough to cause it to stop working). I’ve done the initial things I could think of (check the fuse, check capacitors, etc) and I don’t know much else about them. Anyone else got any ideas on how to test it without hooking it all up in my car just to find out it doesn’t work?

Thanks.

Get a 12V bench power supply, a couple of speakers, and an mp3 player?