bad_ta_05

i am having soo much trouble with my cd player. its a kenwood and all of a sudden teh sound just went out. well i sent it in under warranty and they changed the internals of it and sent it back. i put in about 3 inch stereo wires to make the wiring harness longer and i switched around 2 speaker wires cause they were crossed or so teh diagram i looked at said. and anyway i get it back and it still doesnt work! i sent it back again and they said that it worked fine for them and i get it back and it still doesnt work. what should i do? it powers up but there is just no sound. what do i need to look for? could it be a bad wiring harness? i just have no clue. i also took out the blue tube connectors i had on it and i solders the wires so i knew it made good connections. im lost. can anybody help me out? thanks