What was found
CABIN EMERG LIGHT: WITH THE EMER LTS IN THE ARM POSITION WITH THE MAIN BATTERIES OFF, THE FOLLOWING EMERGENCY LIGHTS FAIL TO ILLUMINATE: THE EXIT SIGN ON THE BULKHEAD BEHIND SEAT 7, THE EXIT SIGN BELOW THE LAVATORY SEAT, THE PATH LIGHT UNDER THE LAVATORY SEAT, AND THE OVERHEAD LIGHT ABOVE THE LAVATORY SEAT. REMVOED AND REPLACED #4 EMERGENCY BATTERY WITH NJA SUPPLIED REPAIRED ASSEMBLY. POWERED ON AND PERFORMED EMERGENCY BATTERY CHARGING. PERFORMED MULTIPLE GOOD OPS/FUNCTION CHECK OF EMERGENCY LIGHTING SYSTEM. WORK DONE IAW CE-680A AMM CH 33-50-06. P/N ON CBS28-1 S/N ON 4421M P/N OFF CBS28-1 S/N OFF 4652M