As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ELEC LIGHT ON OVERHEAD PANEL ILLUMINATED. GROUNDED - YES. PERFORMED BITE OF P5-13 MODULE, FAULT IS BAT CHAR INOP. PERFORMED B737-800 FIM 24-31 TASK 829 TO F3D. FOUND 115VAC AT PINS 4,7,10, P92 C1 AND J9 A4 CBS ARE OPEN. REMOVED AND REPLACED (M5) MAIN BATTERY CHARGER REF B737-800 AMM 24-31-21. REPAIR CONFIRMATION SUCCESSFUL REF FIM 24-31 TASK 829. AIRCRAFT OK FOR ETOPS SERVICE. ALL OPS CKS GOOD.