As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE TOILET CASS MESSAGE AFTER TAKEOFF WITH LAV SMOKE ALARM ACTIVATED RAN QRH, MESSAGE EXTINGUISHED ALARM OFF F/A REPPORTED NO INDICATION OF SMOKE OR FIRE ON INSPECTION. RAN ENGINE WITH APU AIR SWITCH OVER TO BLEED AIR AND NO SMOKE CAUTION MESSAGE WITH EITHER APU OR ENGINE SUPPLYING PACKS NO EXTERNAL ENGINE OIL LEAKS NOTED. SUSPECT FAULTY LAV SMOKE DETECTION SYSTEM. REMOVED AND REPLACED SMOKE DETECTOR UNIT, OPS CHECK GOOD. (K)