Need Help A.S.A.P. , hooked up in dash mp3 player and get no sound

Hello everyone , I am at a loss for words on what happened to me earlier today. I purchased a 96 Ford Explorer Sport yesterday and wanted to change the CD player out and put in my mp3 deck. I removed the old Sony CD unit and unplugged the harnesses, then took the Sony mp3 harness and wired everything up. When I tried to test the mp3 unit it came on and lit up and functioned properly, but I had no sound at all . This unit is almost brand new and was working perfectly in my S-10 I removed it from earlier today. I have rechecked all of my wiring and everything is connected color to color on the harnesses, connections are soldered with shrink tubing and no fuses are blown. I ran a seperate ground straight to the battery and checked it and still nothing. The CD player and the mp3 player worked fine until I switched them and when the mp3 didn't have any sound I switched the CD unit back and now it has no sound either. The factory wiring hasn't been cut and all is as it should be except for the sound. Please if anyone knows what is going on here let me know as I am clueless. Thanks for your time ... RSM

 

I am uncertain, however I wouldn't imagine it would have for the CD unit to have been working when removed. I will check to make sure though ... thanks !!

 

Got it !! ... appears you were right, they had it wired straight to the battery before I hooked it up correctly .... had a factory amp mounted under the passengers side rear panel in the hatch ... took the amp loose and re-wired everything ... works great