As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB IN DEN LEFT PACK DID NOT COME ON AND WE GOT CABIN ALT CAUTION AND FOLLOWED WITH CBAIN ALT WARNING. (FLIGHT 5024 - FILED CLOSED) REF AML 1502615 FOR LH PACK DEFERRAL AND AML 1502517 FOR PASSENGER O2 MASKS DEPLOYED CORRECTIVE ACTION.