As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB PHASE EICAS MSG FWD EQUIP VALVE DISPLAYED EQUIP COOLING VALVE LIGHT ILLUMINATED. STBY POSITION SELECTED AND VALVE LIGHT REMAINS ILLUMINATED. AIRCRAFT DID NOT PRESSURIZE, EMERGENCY DESCENT WAS INITIATED AND RETURN TO AIRPORT. THE VALVE WAS TRANSFERRED IAW MEL 21-58-7. AFTERWARDS THE OVERBOARD EXHAUST VALVE WAS REPLACED. TEST WAS SATISFACTORY.