What was found
REF ASA LP 60513046, REF B737-900 AMM 24-31-21 ATTEMPTED REPLACEMENT OF MAIN BATTERY CHARGER(M5) BP FROM SWA, FOUND BURN MARKS ON FLOOR PANEL BELOW AUX BATTERY CHARGER AND DAMAGE TO AUX BATT CHARGER. GROUNDED - YES. REF B737-900 AMM 24-31-31, B737-900 WDM 24-31-12-2, 24-31-11-2. POSITIVE TERMINAL LUG HAS ARCING DAMAGE. REMOVED AUX BATTERY CHARGER IAW AMM 24-31-31. AUX BATTERY CHARGER HAS ARCING DAMAGE AT LEADING EDGE & UNDERSIDE. RACK HAS ARCING DAMAGE. REINSTALLED AUX BATTERY CHARGER INTO RACK. REPLACED BOTH TERMINALS ON M5 BATTERY CHARGER AND M3055 AUX BATTERY CHARGER REF B737 SWPM 20-30-11. MAIN BATTERY CHARGER REPLACED ON ASA LP 60513037. AUX CHARGER M3055 REPLACED. OP TEST NORMAL AMM 24-31-31-400-801. AUX CHARGER RACK TRAY REPLACED AMM 20-10-07. FLOOR PANEL ADDRESSED ON LOGPAGE 60585654.