As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER ENGINE START, L BLEED ISOLATION VALVE DISCRETE LIGHT AND YELLOW EICAS MESSAGE ON WHEN VALVE COMMANDED CLOSED. CREW RETURNED TO GATES (BTB). MTC SWAPPED L+C ISOLATION VALVES IAW B767 AMM 36-11-04 OPS/LEAK CHECK GOOD FOR L ISOLATION VALVE AC REMAINS NO ETOPS. A/C RETURNED TO SERVICE.