As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DECLARED EMERGENCY - AT INITIAL DESCENT FM FL350 CABIN ALT WARNING HORN SOUNDED & CABIN ALT LIGHT CAME ON COULD NOT CONTROL ALT IN AUTO OR MANUAL PER QRH. REMOVED AND REPLACED NR 1 ENGINE BLEED AIR REGULATOR, NR 1 ENGINE PRECOOLER CONTROL VALVE, NR 2 ENGINE HIGH STAGE PRESSURE REGULATOR PER AMM.