As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED THAT THE AFT CARGO DOOR INDICATED OPEN AND COULD NOT PRESSURIZE ACFT. AN EMERGENCY WAS NOT DECLARED, ELECTED TO RETURN TO DEPARTURE AND LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED AND FOUND CARGO DOOR WAS NOT PROPERLY SECURED AND THE LATCH WAS OUT. MAINTENANCE SECURED DOOR IAW AMM AND OPS CHECKED GOOD.