As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BOTH AFT LAVATORY SMOKE ALARMS ACTIVATED AFTER TAKEOFF. FLIGHT ATTENDANT REPORTED AN ELECTRICAL TYPE SMELL IN AFT CABIN. FLIGHT WAS RETURNED TO MSP AND LANDED WITHOUT INCIDENT. MAINTENANCE REPLACED BOTH HEAT EXCHANGERS AND RIGHT AIR CYCLE MACHINE, OPERATIONAL CHECK NORMAL.