As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EMERGENCY ESCAPE LIGHT, AT AISLE ROW 25, TURN ON WHEN TRANSFERRING AC ELECTRICAL POWER SOURCES AND REMAINED ON WITH EMERGENCY EXIT LIGHT SWITCH IN ARM POSITION. AIRCRAFT RETURNED TO GATE. BATTERY PACK WAS DEFECTIVE. REPLACED THE BATTERY PACK, SYSTEM CHECKED OK.