DiagramShow
My best guess is that I need to buy a new volume wheel, but I don't think that's the problem.
Edit: No sound from headphones either...
Update: Upon further testing, I found that a ground wire was not connected to the amp. I turned it on, and the splashscreen sound played, but I went into Tetris and heard nothing. When I plug the headphones in, the speaker still plays, probably because my headphones stick out a ton. I'll probably buy a new jack and volume wheel, hook it up and see what happens.