As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 6429 TPA-FLL AT 500 FEET, LAVATORY SMOKE EICAS WARNING MESSAGE APPEARED. FLIGHT ATTENDANT REPORTED LAVATORY SMOKE DETECTOR SOUNDING AND ALARM. NO VISIBLE SMOKE. RAN QRH. STILL NO VISIBLE SMOKE NOTED FROM FLIGHT ATTENDANT. RETURNED TO LAND IN TPA. MAINTENANCE UNABLE TO DUPLICATE FAULT. PERFORMED LAVATORY SMOKE DETECTION SYSTEM TEST IAW EMB 145 MM 26-14-00-700-801-A. OPS CHECK GOOD.