As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BUSSES WOULD NOT STAY POWERED BY APU OR GROUND POWER. BURNING SMELL FILLED COCKPIT. COULD SMELL 4 ROWS INTO CABIN. ALL T/R CB'S POPPED AND BATTERY CHARGER & NORMAL EQUIP COOLING FAN POPPED. R & R APU GENERATOR AND BATTERY CHARGER, APU TRANSFORMER, APU FIRE LOOP IAW MM. U FIRE LOOP IAW MM.