As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CABIN OVERHEAD EMERGENCY LIGHTS ARE FLASHING ON AND OFF DURING FLIGHT. REMOVED DEFECTIVE AFT EMERGENCY BATTERY P/N:7450LS-00, AND INSTALLED A CUSTOMER SUPPLIED TESTED EMERGENCY POWER SUPPLYS/N:005594 P/N:7450LS-00, S/N:006503. PERFORMED SATISFACTORY OPS CHECK, NO DEFECTS. CLOSED OUT ALL GAINED ACCESS AND RETURNED AIRCRAFT BACK TO ORIGINAL CONFIGURATION. WORK PERFORMED IAW AMM 32-52-01.