As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB DTW-HPN, FOUND THAT THE AIRCRAFT WOULD NOT PRESSURIZE. FOLLOWED COCKPIT OPERATING MANUAL PROCEDURES AND RETURNED TO DTW WITHOUT FURTHER INCIDENT. FOUND THAT BOTH THE INNER AND OUTER AFT CARGO DOORS WERE LATCHED IN THE OPEN POSITION. ALSO, FOUND THAT THE DOOR WARNING SYSTEM WAS INOPERATIVE. REPLACED THE AFT CARGO DOOR WARNING SWITCH.