As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED A AFT LAVATORY SMOKE DETECTION WARNING WITH SMOKE DETECTOR ALARM, DURING CLIMB. NO SMOKE WAS SEEN OR SMELLED. CREW DECLARED AN EMERGENCY AND RETURNED. FIRE DEPARTMENT INSPECTED LAVATORY AND FOUND NO SIGNS OF SMOKE OR FIRE. AFT LAV SMOKE DETECTOR WAS REPLACED PER AMM.