2001 Chevy S-10

I have a 2001 Chevy S-10, a buddy of mine hooked up a subwoofer and amp for me in it. About a week afterwards I went to start my truck and all it did was turn over. We put a new fuel pump on it and it ran fine without the bed on it, when I put the bed back on the truck would not start. I finally un hooked the speaker and amp and the truck ran good with the bed on. I was driving down the road and turned the radio on and the truck died, and all it will do is turn over. I'm thinking that something has shorted out. Any help will be great. Thank you for your time.