As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE AIRCRAFT FAILED TO PRESSURIZE IN ALL FLIGHT MODES. THE CREW RETURNED TO POINT OF ORIGIN. REMOVED THE OUTFLOW VALVE AND PRESSURE CONTROLLER. SEALED SMALL LEAK IN TRUNNION AREA, PRESSURIZED AIRCRAFT SEVERAL TIMES WITH APU AND ENGINES, NO DEFECTS NOTED.