As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 2931 - OUTBOUND OF MSP, BATTERY FAULT LIGHT AND BOTH RIGHT AND LEFT DISCONNECT LIGHTS ILLUMINATED. CREW FOLLOWED QUICK REFERENCE HANDBOOK AND COULD NOT RESET. AIR TURNBACK TO MSP. MAINTENANCE REPLACED RIGHT BATTERY FAULT TRANSFORMER AND THE SERIES PARALLEL RELAY. COMPLETED GROUND RUNS. OPS CHECK GOOD. REFERENCE MALA975447.