An SD kit is used for flashing firmware BINs modified by Universal Firmware Patcher so that a device can use 'unlocked' maps and is generally used because modern devices like yours are difficult for users to get into preboot. Mostly the reasons for an SD flash not working are either because an incorrect HWID folder or last_id.bin is present because of previous usage of the kit. Your EU Drive Assist 51 has HWID of 2590, the similarly named Drive/DriveSmart 51 and DriveLuxe51 have HWIDs of 2586 and 2589 respectively. Flashing incorrect files can permanently and irretrievably brick a device. You'll need to access Master zone for more detailed assistance.