As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FIRST OFFICER FOUND EMER LTS LIFTED IN THE ARM POS WITH NO APU ON OR GPU PLUGGED IN. STARTED APU TO CHARGE BATTERIES, AFTER 10 MINS, LIGHTS ARE STILL FLICKERING WHEN TURNED O. R & R ALL 4 ESPU BATTERY PACKS IAW MM 33-51-17. OPERATIONS CHECKED GOOD. SEE MX OPERATIONS FOR PARTS DISPOSITION. EMER LIGHTING BATTERY PN 2013-1A NR 2 SN 104905 NR 3 SN 74536 NR 4 SN 103795.