As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED THAT DURING FLIGHT THE EMERGENCY BUS FDR AND BATTERY CUT OFF LIGHTS ILLUMINATED. NO VOLTAGE WAS INDICATED ON THE VOLTAGE METER. THE MAINTENANCE TEAM TROUBLESHOT AND DETERMINED A DC GROUND FAULT PROTECTION PAN P/N 50284-003 S/N P1198C. THE DEFECTIVE UNIT WAS REMOVED AND AN OVERHAULED UNIT WAS INSTALLED. OPERATIONAL CHECKS WERE SATISFACTORY AND THE AIRCRAFT WAS RETURNED TO SERVICE