As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AFT CARGO DOOR INDICATION ALERT AFTER TAKEOFF, AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO LAX WHERE IT LANDED SAFELY WITHOUT FURTHER INCIDENT. MAINTENANCE REPLACED THE AFT CARGO DOOR PROXIMITY SENSOR AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK PER AMM 52-71-12.