As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A PREFLIGHT TEST, WHEN SELECTING EMERGENCY LIGHTS ON, THE EMERGENCY LIGHT BATTERY FAULT EICAS MESSAGE DISPLAYED. THE AIRCRAFT WAS GROUNDED. MAINTENANCE REPLACED POWER SUPPLY IAW AMM 33-50-01, AND PERFORMED A SATISFACTORY OPERATIONAL CHECK.