As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LAX - CREW REPORTED AFTER TAKEOFF LEFT ENGINE BLEED OFF ANNUNCIATED WITH APU BLEED AIR ON MEL. EMERGENCY DECLARED FLIGHT RETURNED LAX LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. REPLACED LEFT ENGINE REVERSE FLOW CONTROL VALVE. SYSTEM GROUND CHECK NORMAL OPERATION.