What was found
(CAN) ADVISORY: BATTERY CHARGER FAULT, INFO: 24 BATT CHARGER FAULT BATT CHARGER 2 INOP DURING TAXI OUT. CREW CONTACTED MAINTENANCE, RESET CARRIED OUT UNDER MAINTENANCE GUIDANCE. A/C DEPARTED AT 05:26UTC, AIRBORNE AT 05:53UTC . FAULT REPEATED AFTER TAKE OFF, A/C RETURNED BACK TO AIRPORT.