As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED THAT UPON AIRCRAFT POWER UP RECEIVING AN EMERGENCY LIGHTS NO1 BATTERY FAIL FAULT MESSAGE. THE MAINTENANCE TEAM FOUND THE NO1 EMERGENCY POWER SUPPLY WAS DEFECTIVE. THE UNIT WAS REMOVED AND REPLACED WITH A REPAIRED POWER SUPPLY. OPS CHECKS SATISFACTORY AND THE AIRCRAFT WAS RETURNED TO SERVICE.