1995 Mariah Z 272 Barchetta wiring
 

I bought a 1995 Mariah Z 272 Barchetta more than a year ago, this is my first boat. Now the stereo and CP radios are not getting power, the panel fuses seem ok. The wiring behind the panel is big mess, looks like a bird's nest. Any recommendation of what to look for just to get the stereo fixed? Not sure if rewiring the entire panel should something that I can tackle, I've work on my cars but never done any work on a boat