As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMBOUT FROM BOS AIRCRAFT WOULD NOT PRESSURIZE, TRIED BOTH AUTO AND MANUAL CONTROLLERS. EMERGENCY DECLARED, A/C RETURNED TO BOS LANDED SAFELY. INSPECTED A/C, FOUND CARGO DOOR NOT PROPERLY CLOSED. OPENED AND CLOSED CARGO DOOR, PERFORMED PRESSURIZATION CHECK. NO DEFECTS NOTED.