As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: UPON PRE-FLIGHT, FOUND THAT EMERGENCY EXIT LIGHTS ON THE OVERHEAD PANEL WOULD NOT ILLUMINATE DURING POWER CHANGES OR WITH THE EMERGENCY LIGHT SWITCH IN THE ON POSITION. MAINTENANCE FOUND BATTERY PACK B5-103 BAD AND REPLACED BATTERY PACK PER AMM 33-53-00.