As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AUS - CREW REPORTED AFT CARGO DOOR OPEN LIGHT ILLUMINATED AFTER TAKEOFF AND AIRCRAFT WAS HAVING DIFFICULTY PRESSURIZING. EMERGENCY DECLARED RETURNED AUS LANDED WITHOUT INCIDENT. CHECKED AND ADJUSTED AFT CARGO DOOR LIGHT SENSOR. PERFORMED BITE TEST ON BOTH PRESSURE CONTROLLERS - NO FAULTS FOUND. PRESSURIZED AIRCRAFT - PRESSURIZATION NORMAL. SYSTEM GROUND CHECKED NORMAL OPERATION.