As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: FOUND FAULT "EPSU BATTERY EMERG L". T/S IAW FIM 33-51-00 & C/W OPS TEST OF BATTERY OF POWER SUPPLY UNIT-EMERGENCY IAW AMM 33-51-00, RED BATT FAULT LED LT COMES ON. MAINTENANCE REPLACED THE BATTERY PER 33-51-38.