As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING SERVICE CHK, FOUND L2 DOOR EMERGENCY SIGN TO NOT COME ON AS WELL AS AFT GALLEY OVERHEAD SIGN. DURING TROUBLESHOOTING, SWAPPED BATTERY PACKS OF M1672 AND M1673 IN THE AFT GALLEY. FAULT FOLLOWED CONFIRMING IT NEEDS THE BATTERY PACK REPLACED. SWAPPED BATTERY PACKS TO ORIGINAL CONDITION IAW AMM 33-51-06-960-805. R & R THE BATTERY PACK M1673 IAW AMM 33-51-06-960-805. OPS CHECK GOOD, NO DEFECTS NOTED.