As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ELEC CAUTION LIGHT ILLUMINATED DURING ENGINE START. LIGHT ILLUMINATED AND REMAINED ON. GROUNDED - YES. TROUBLESHOOTING PER B737-9 IFIM 24-31-00. PERFORMED ELEC LIGHT BITE TEST. FOUND AUX BAT CHGR INOP 1 MESSAGE. R & R MAIN & AUXILIARY BATTERY IAW B737-9 AMM 24-31-11. R & R AUXILIARY BATTERY CHARGER IAW AMM 24-31-31. E3-3 AUX, E2-1 MAIN