What was found
UPON REINSTALLATION OF THE PILOT'S SIDE MAIN CIRCUIT BREAKER PANEL OVERLAY, THE ATTACHING SCREW INSTALLED IN THE AFT CENTER MOUNT HOLE CONTACTED THE VERTICAL LEG OF A BUSS BAR. THE BUSS BAR IS LOCATED DIRECTLY BEHIND (OUTBOARD OF THE MOUNTING NUTPLATE. THE SCREW BEING INSTALLED WAS ONLY SLIGHTLY LONGER, APROXIMATELY .0625 INCH, THAN THE ONE ORIGINALLY INSTALLED. WHEN THE AIRCRAFT WAS POWERED UP, AN ELECTRICAL SHORT CIRCUIT TO GROUND OCCURRED RESULTING IN DAMAGE TO THE CIRCUIT BREAKER PANEL, PANEL OVERLAY, SCREW, NUTPLATE, AND WIRING.