Stereo won't turn on in 1996 Pontiac Grand Prix

I recently tried to install an aftermarket stereo into my 1996 grand prix. Everything was working fine until I fit it into the housing, saw a spark from behind, and the entire stereo system turned off. I checked the fuse of the stero and double checked my wiring and everything seemed fine and secure, though I rewired everything to be safe. I tried hitting the reset button like the manual said but nothing happened. I decided to reconnect the previous stereo system and while everything lights up the clock nor the stereo work at all. No sounds even come from the speakers (eg: binging when keys are in the ignition and doors are open) unless I press the power lock on the door. Did I disconnect something internally, or is there something else I may have blown?