As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CABIN ALTITUDE BEGAN CLIMBING AS DECSENT INITIATED INTO DEN AND CONTINUED TO CLB AT APPROX 450FPM . RAPID DECSENT INITIARED AND CABIN ALTITUDE DID NOT COME UNDER CONTROL UNTIL CABIN AND AIRCRAFT ALTITUDE WERE COINCIDENT AT APPROX 10000 FEET. REPLACED BOTH SAFETY VALVES REF AMM 21-31-52-400-001-A.