As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAIN CARGO DOOR WON'T OPEN ON APU POWER. GROUND HANDLING BUS NEEDS EXTERNAL POWER TO ENERGIZE RELAY TO OPEN DOOR. EXT POWER INERLINK FUSE B FOUND BROKEN. FUSE REPLACED. MAIN DECK CARGO DOOR OPENED SEVERAL TIMES WITH ONLY APU POWER. SYS OK FOR FURTHER SEVICE. FINAL CLOSED.