As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: INTERMITTENT, VERY BRIEF FLASH OF LAVATORY SMOKE ANNUNCIATOR ON OAP ACCOMPANIED BY CHIMES IN CABIN AND RED LAVATORY LIGHT CAME ON AND OFF VERY BRIEFLY IN UNISON WITH CHIMES AND LAVATORY SMOKE ANNUNCIATOR. RED LIGHT FLICKERED AT ALL LAVATORIES. MAINTENANCE PERFORMED SATISFACTORY OPERATIONAL CHECK OF LAVATORY SMOKE DETECTORS PER MM 26-19-00.