As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: FAULT MESSAGE DISPLAYED DURING SYSTEM TEST FOR EMERGENCY POWER SUPPLY UNIT 15WL. MAINTENANCE CYCLED CIRCUIT BREAKERS AND RESEATED THE BATTERY FOR EMERGENCY POWER SUPPLY UNIT 15WL PER AMM 33-51-38. A SATISFACTORY OPERATIOANL CHECK WAS ACCOMPLISHED.