As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: SHORTLY AFTER LEVEL OFF AT FL370, CABIN ALTITUDE ALERT SOUNDED AND FLASHED, MANUALLY DEPLOYED MASKS. AIRCRAFT DIVERTED TO AND LANDED SAFELY AT PIT. *GVI OF APU AIR DUCT BOOT. REMOVED AND REPLACED OUTFLOW VALVE (AALA202512088232). ALSO REMOVE AND REPLACED BOTH POSITIVE PRESSURE RELIEF VALVES (AALA202512164641), (AALA202512165396).