Is my car stereo head unit fried?

My car stereo head unit shuts off when I open a door or turn to a certain volume?

• I have an aftermarket sony head unit, and recently installed two subwoofers powered by an amp. I had no problems until I just recently had to replace my starter motor. My car wouldn't start so I tried charging battery and jumping the battery and my stereo stopped working. The guys that replaced and installed the new starter also had to replace a stereo fuse I believe and now I have all these problems. the stereo also doesn't play cds either. What is the problem and how do I fix it?

• Answer:

  It sounds like there might be a problem with your battery or charging system wiring. Check the connections at your battery; make sure they're tight. There should be a connection between the battery's negative terminal and the vehicle's chassis; make sure that's still in place, clean, and tight. If it's been disconnected, then your cabin accessories will be starved for power.