Try a different USB cable or port (USB 2.0 is more stable than 3.0 for flashing).
Modern MTK chips (MT67xx, MT68xx, etc.) have a "Secure Boot" feature. If the Preloader is broken, you need to use an . Open the Bypass Tool. Click "Disable Auth." mtk preloader repair tool fixed
The industry standard for MTK devices.
You are likely using the wrong firmware for your specific sub-model or region. Conclusion Try a different USB cable or port (USB 2