As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR RETURN. AFTER LIFT OFF RECEIVED RECEIVED AVEC EXTRACT FAN FAULT WITH BLOWER FAN ON MEL. UNABLE TO PRESSURIZE AC. FOUND AIR INLET CHECK VALVE STUCK OPEN. VALVE DID CLOSED AFTER CLAMP WAS REMOVED. NEW VALVE AND CLAMP PLACED IN FLT DECK. REPLACED AIR CHECK VALVE PER AMM 21-26-56. TESTS GOOD. PRESSURIZED PER JRH 2-40-80. ALL TESTS GOOD.