As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAIN CARGO DOOR OPEN LIGHT CAME ON AFTER ENG START AND BLOCK OUT. AIRCRAFT BACK TO BLOCK AND GROUNDED BY MAINTENANCE. MAINTENANCE OPERATED MAIN CARGO DOOR IAW 52-00-00 TO FULL EXTENSION WITH NO FAULTS FOUND. CLOSED DOOR AND VERIFIED LATCHED BY THE EXTERNAL VISUAL INDICATORS AND THE PANEL DELUMINATED. AIRCRAFT RETURNED TO SERVICE.