As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ACFT FAILED TO PRESSURIZE AFTER TAKEOFF. RETURNED TO DEPARTURE AIRPORT. NO EMERGENCY WAS DECLARED AND ACFT LANDED SAFELY. DURING TROUBLESHOOTING FOUND AFT BAGGAGE DOOR SEAL FROZEN. SEAL THAWED AND WATER DRAINED. ACFT WAS RETURNED TO SERVICE.