As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
OUTFLOW VALVE STAYED FULL CLOSED WHEN ON THE GROUND. ACFT GROUNDED. PERFORMED GROUND VERIFICATION TASK REF FIM 21-31-801 AND 21-31-802. GROUND TEST ON NR 1 AND NR 2 PRESSURE CONTROLLER. OPS NORMAL. CODE NR 57 FOUND ON PRESSURE CONTROLLER NR 2 CLEARED AND RESET.