Speakers/sub not working right - valor its-700w head unit

ok so i just came home from school the other day and my car has been sitting for about 3 weeks.

Car is a 1995 mitsubishi eclipse gsx

I have a valor its-700w head unit and dual speakers, sub and amp.

All of the speakers are quieter, i have to turn them up to 25 to listen instead of the usual 12-14. Also the back left speaker is not working, but when i switched the output cable with the back left, it started working and the back right stopped working. The back left was working at full volume two days ago and i watched it go out when i turned up the volume! Also if i unplug the subwoofer out cable and just touch it to the input cable the sub will hit randomly, so it still works. So i came to the conclusion that something is wrong with the head unit. Do you think thats accurate? I was actually looking to sell this car soon and now i have to deal with this! I guess it doesn't want to leave me


As of now i have the head unit basically apart. I'm not good with electronics but nothing looks wrong to me. No corrosion that i can tell. What could it be? Anyone have a similart problem with a valor head unit? Could this be a problem with the cars electrical system?