As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHORTLY AFTER TAKEOFF, THE CREW NOTICED A CARGO DOOR ANNUNCIATOR ILLUMINATED. THE CREW PERFORMED AN AIR-TURN-BACK. THE DOOR WAS FOUND TO BE SECURE. MX CLEANED THE POXI SWITCHES OF ICE AND SNOW, OPENED AND CLOSED THE CARGO DOOR. THE AC WAS RETURNED TO SERVICE WITH NO FURTHER DEFECTS. (K)