As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LAX - CREW REPORTED AIRCRAFT WOULD NOT PRESSURIZE AFTER TAKE OFF. NUMBER 2 CABIN PRESSURE CONTROLLER CURRENTLY ON PLACARD. FLIGHT RETURNED LAX LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. REPLACED CABIN PRESSURE OUTFLOW VALVE ACTUATOR. SYSTEM GROUND CHECK NORMAL OPERATION.