As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING REINSTALLATION OF LEFT UPPER DOOR SLIDE PACK TO FACILITATE OTHER SCHEDULED MAINTENANCE, A CHECK OF THE EMERGENCY POWER RESERVOIR, PER AMM 52-23-13-406-045, FAILED (BATTERY OK GREEN LIGHT DID NOT ILLUMINATE). TROUBLESHOOTING FOUND BURN MARKS ON CIRCUIT BOARD FROM LEFT BATTERY PACK (M7037). REPLACEMENT OF BATTERY PACK OCCURRED WITH SATISFACTORY OPS CHECK RESULTS.