As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CABIN PRESSURIZATION FAILED 35,000 FT CABIN OUTFLOW VALVE CLOSED. DESCENDED TO 24,000 TO REDUCE CABIN ALTITUDE. CABIN ALTITUDE STABILIZED AT 5500. AIRCRAFT MADE AN UNEVENTFUL LANDING AT DAL. REPLACED PACK VALVE AND OP CHECKED PER BOEING M/M.