My girlfriend just recently purchased a 2006 cobaltChevrolet Cobalt from a previous co-worker. Everything seemed ok with it besides the stereo. No sound is coming out of any of the speakers at all. All functions work on the stock stereo and all displays work and every now and then when we start the car we will hear a slight sound out of the speakers. It's not just the front speakers it's the rear as well. I pulled the stereo out and all wires look connected so I'm at a loss. Any help is greatly appreciated.