As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LBB CREW REPORTED AFT CARGO DOOR WARNING & UNABLE TO PRESSURIZE. EMERGENCY DECLARED, FLIGHT RETURNED LBB LANDED WITHOUT INCIDENT. VERIFIED AFT CARGO DOOR CLOSED & LOCKED. ACCOMPLISHED GND PRESS CHECKS WITH NO DISCREPANCIES. SYS GND CHECKED NORMAL OPERATION CLOSED.