As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PHX - AIR TURNBACK - FLT 0807 - AFTER TAKEOFF FROM PHX EN ROUTE TO SFO PASSING APPROXIMATELY 500 AGL THE FWD CARGO DOOR UNLOCK WARNING CAME ON. AIRCRAFT TURNED BACK TO PHX AND ON DOWNWIND RETURN FOR LANDING THE WARNING LIGHT WENT OUT. MAINTENANCE REPLACED THE THE FWD CARGO DOOR PROXIMITY SWITCH, SWITCH WAS ADJUSTED TO CORRECT TOLERANCE IAW AMM 52-71-12-401, AND OPERATIONAL CHECK WAS GOOD.