As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLIMBING THROUGH FL250 CABIN ALTITUDE WARNING HORN SOUNDED. CABIN ALTITUDE INDICATED 10,000+ AND CLIMBING. ALL SYSTEM SWITCHES WERE IN THE NORMAL POSITIONS (PACKS IN AUTO). DESCENT STARTED AT THE SAME TIME AS THE OUTFLOW VALVE WAS FULLY CLOSED USING THE MA