As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: WHILE ACCOMPISHING EMERGENCY LIGHTING BITE TEST, FORWARD EMERGENCY POWER SUPPLY UNIT BATTERY FAULT DISPLAYED. MAINTENANCE REPLACED THE BATTERY FOR THE FORWARD EMERGENCY POWER SUPPLY UNIT PER AMM 33-51-38 AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK.