As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. EMERGENCY LIGHT SYSTEM FAULT. EPSU INT LOAD FWD L OCCURED WHILE PERFORMING THE FUNCTIONAL CHECK DURING THE PS MAINTENANCE CHECK. SUPPLEMENTAL REPORT: REPLACED EMERGENCY POWER SUPPLY UNIT 10WL (AALA202012049014) AND 12WL (AALA202012079025), PER AMM 33-51-13. ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK.