As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) NR 1 BATTERY OVERTEMP, CHARGER FAIL LIGHT CAME ON AFTER START UP. LT & RT BATTERIES SWAPPED PROBLEM TRANSFERRED TO RT SIDE. SUSPECT OVERTEMP SWITCH IN BATTERY FAILED. LT BATTERY REPLACED, ENGINE GROUND RUN. BATTERY OVERTEMP AND CHARGER FAIL LIGHT NOT ON. CHECKED SERVICEABLE.