As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING AN OVERNIGHT LINE CHECK, THE EMERGENCY EXIT SIGN IN THE MID-CABIN CEILING AND ABOVE THE LT OVERWING EXIT FAILED TO ILLUMINATE. MX FOUND THE ASSOCIATED BATTERY PACK TO BE DEFECTIVE AND REPLACED IT. SYSTEM OPERATION WAS NORMAL AFTER THE BATTERY PACK WAS REPLACED. (K)