As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER SECOND ENGINE START NR 2 ENG, FWD EQUIPT VAL EICAS MSG WITH ASSOCIATED VALVE LIGHT ON EQUIPMENT COOLING PANEL. WENT TO STANDBY, NO HELP. RETURN TO GATE. VALVE LIGHT AND EICAS MSG WENT OUT WHEN NR 1 ENG SHUT DOWN. FWD TO MCO AND PLACARD PER MEL 21-58-07. VALVE LOCKED CLOSED T/S FWD EQUIP VALVE MSG PER FIM. NO FAULTS FOUND. EQUIPMENT COOLING SYS CKS GOOD.