As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DC ESSENTIAL BUS 1 OFF WITH BATTERY 1 DISCHARGE. RAN QRH 5.11 & DIVERTED. UPON TROUBLESHOOTING FOUND GCU 1 TO BE DAMAGED. R & R GCU 1 IN LICC IAW AMM 24-21-19. OPERATIONS CHECKED SATISFACTORY, NO DEFECTS NOTED AT THIS TIME. ACFT OK FOR SERVICE.