As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT NOT GROUNDED: MAINTENANCE REPORTS WHILE ACCOMPLISHING OPERATIONAL TEST OF EMERGENCY LIGHTS IAW JOB CARD PS21, FOUND FAULT AT EPSU 12WL BATTERY OVERHEATING. MAINTENANCE REMOVED AND REPLACED THE BATTERY AT EPSU 12WL IAW AMM 33-51-38. OPS CHECKS GOOD.