As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT OUT OF SERVICE UNTIL 01/25. SHORTLY AFTER TAKEOFF BOTH LAVATORY SMOKE ALARMS WENT OFF. FLIGHT ATTENDANTS REPORTED BURNING SMELL. COMPLIED WITH QRH 26.9 & RETURNED TO FIELD. MULTIPLE CBS PULLED IAW CHECKLIST. COMPLIED WITH WO 00244014 & 00244013. R & R 7AC BALLAST IAW LOG PAGE 531730.