As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: L4 SMOKE ALARM ENROUTE. NO SMOKE DETECTED. FLIGHT CREW TURNED OFF WATER HEATER AND CLOSED AFT LAVATORY PER MOC INSTRUCTIONS. MAITENANCE ACCOMPLISHED TSM 26-17-00-810-801-A AND FOUND NO FAULTS WITH THE SMOKE DETECTION SYSTEM AND RESET THE LAVATORY WATER HEATER.