As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 3921 REPORTED CARGO SMOKE LIGHT ILLUMINATING FOR 3 TO 4 SECONDS THEN EXTINGUISHING. FLIGHT ATTENDANT INSPECTED THE AREA AND FOUND NO SMOKE OR FIRE. MAINTENANCE REMOVED AND REPLACED THE FORWARD SMOKE DETECTOR AND OPERATIONAL CHECKED THE SYSTEM, ALL CHECKS GOOD.