As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT MX - ONT - WHILE PERFORMING 4 A-CHECK MX PERSONNEL WAS PERFORMING OP'S CHECKS ON FWD BAGGAGE SMOKE DETECTOR AND IT FAILED. MX PERSONNEL REMOVED AND REPLACED FWD CARGO SMOKE DETECTOR OPERATIONALLY CHECKED SATISFACTORY. AIRCRAFT WAS RELEASED TO RETURN FOR SERVICE.