What was found
CABIN EMERG LIGHT: THIRD SIMILAR WRITE UP IN RECENT HISTORY: WITH NO POWER ON AIRCRAFT AND EMER LIGHTS SELECTED TO ARM THE EMERGENCY LIGHTS ARE INOP. WITH EMER LIGHTS SELECTED TO ON THE ALL ILLUMINATE. PER THE PREFLIGHT CHECKLIST THE LIGHTS SHOULD ILLUMINATE WITH ARM SELECTED AND MAIN SHIP POWER OFF. REMOVED FAILED #1 EMERGENCY LIGHT BATTERY P/N: CBS28-1, S/N: 3809M AND REPLACED WITH A CUSTOMER SUPPLIED REPAIRED BATTERY P/N: CBS28-1, S/N: 2505M. PERFORMED SATISFACTORY OPS CK OF EMER LIGHTS REF CE680A AMM 33-50-06.