As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EXPERIENCED SMOKE IN THE COCKPIT AT THE GATE PRIOR TO DEPARTURE. THE FLIGHT CREW QUICKLY POWERED DOWN THE AIRCRAFT; NO PASSENGERS WERE ON BOARD. MAINTENANCE FOUND THE GROUND SERVICE CONTACTOR TO BE THE PROBLEM AND ONE PHASE OF THE THREE PHASE GROUND POWER CIRCUIT BREAKER OVERHEATED AND DID NOT OPEN. GROUND POWER CONTACTOR AND KLIXON CIRCUIT BREAKER P/N BACC18AE25 REPLACED.