As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AN AIR TURN BACK DUE TO MASTER WARNING FOR AFT BAGGAGE DOOR. THERE WAS A LOSS IN PRESSURIZATION, CHECKLIST WAS AUCTIONED BY THE FLIGHT CREW AND LAST ITEM ON CHECKLIST FOR THE SCENARIO WAS TO LAND. AFTER SHUTDOWN, RAMP ADVISED THAT THE AFT BAGGAGE DOOR HANDLE WAS "POPPED OUT". AFT BAGGAGE DOOR CYCLED BY FLIGHT CREW, CHECKED SERVICEABLE IAW ELEMENTARY MAINTENANCE.