As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STRONG BURNING ELECTRICAL SMELL MAIN CARGO COMPARTMENT T/S FOUND APU BATTERY SMOKING WITH A HEAVY BURNT SMELL. R&R APU BATTERY REF AMM 24-31-03-4. ALSO R&R APU BATTERY CHARGER REF AMM 24-31-04-4 PRECAUTIONARY. OPS CK'D GOOD. A/C OK FOR SERVICE