As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 5158 - AFTER TAKEOFF AIRCRAFT WOULD NOT PRESSURIZE. RECEIVED OTBD COOL CAUTION AND INBD COOL FAIL MESSAGES. DECLARED EMERGENCY, RETURNED TO BOS, LANDED WITHOUT INCIDENT. FOUND O/B COOL VALVE OPEN. PERFORMED MEL PROCEDURES TO ENSURE VALVE RESET TO CORRECT POSITION. REMOVED CONNECTORS. NO FURTHER DEFECTS.