As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED. EMERGENCY POWER SUPPLY UNIT AT FLOOR ROW 11 ABC HAS BATTERY FAULT WHEN TESTED. REMOVED AND REPLACED EMERGENCY POWER SUPPLY UNIT BATTERY AT FLOOR ROW 11 ABC. OPERATIONS CHECK GOOD. NO FURTHER DEFECTS. REFERENCE AMM 33-51-38.