As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAIN CARGO DOOR LIGHT ON WHILE STARTING ENGINES ON PUSHBACK MTX ENTERED A/C AND FOUND MAIN CARGO DOOR NOT FULLY LOCKED, VENT DOORS WIDE OPEN. CLOSED AND LOCKED MAIN CARGO DOOR IAW B767 AMM 52-33-00. VERIFIED DOOR FULLY CLOSED AND LOCKED.RETURNED A/C TO SERVICE.