As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE EXIT SIGNS AND EMERGENCY LIGHTS DID NOT COME ON WHEN THE GROUND POWER FAILED ON THE GROUND. THE COCKPIT SWITCHES WERE IN THE ARMED POSITION I, TRIED THE EMERGENCY BUTTON ON THE FAP AND STILL DIDNT WORK. R & R DEU-B 300 RH6 IAW 23-73-47, TESTS PASSED, BUT LIGHTS STILL WILL NOT POWER. REMOVED AND REPLACED 10WL EPSU AND BATTERY IAW MM 33-51-38. OPS CHECKED GOOD. REMOVED AND REPLACED EPSU AND BATTERIES IAW 33-51-38 11WL AND 12 WL. OPS CHECKED OK.