As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DID NOT PRESSURIZE DURING CLIMBOUT WITH EQUIP COOLING OVERHEAT MESSAGE. QRH PROCEDURE PERFORMED. CABIN OUTFLOW VALVE FULLY CLOSED. DIFF PRESS .08 MAX. C.A.T HAD FWD DK SUP FLOW AND FWD EQU SUP FLOW EICAS MSG. FOUND OVERBOARD EXHAUST VALVE NOT LOCKED CLOSED OVERCENTER AFTER EXTENSIVE T/S PER FIM 21-58-00. PRESSURIZED AIRCRAFT WITH APU AIR 3 LBS POSITIVE. NO LEAKS FOUND. OUTFLOW VALVE OPN NORMAL IN STDBY AND AUTO 1 AND AUTO 2. EXHAUST VALVE IS ON MCO/PLACARD PER MEL 21-58-01.