What was found
DEN - FLIGHT 6014, THE CREW REPORTED A BURNT ELECTRICAL SMELL IN THE COCKPIT WHEN STARTING THE APU WITH GROUND POWER ASSIST. MAINTENANCE INSPECTED THE GPU & APU CONTACTOR, WITH NO DEFECTS NOTED, STARTED THE APU AND WAS UNABLE TO DUPLICATE THE DISCREPANCY, AND THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE.