As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UPON ROTATION OF FLIGHT #3655, CARGO SMOKE NWS ILLUMINATED AND AFT CARGO SMOKE ILLUMINATED. FA'S DID NOT SMELL SMOKE, NO SMOKE NOTED. CREW DID NOT BLOW BOTTLES, RETURNED TO MSP W/FIRE TRUCKS STANDING BY. AIR RETURN TO MSP. MAINTENANCE COMPLETED NRWC #169910 W/CONT CARDS. REPLACED AFT CARGO SMOKE DETECTOR, FLT DECK CONTROL UNIT AND REPAIRED CHAFFED WIRES TO SMOKE DETECTION AND EXTINGUISHING SYSTEMS CHECK GOOD.