1.Download the firmware

betaflight_4.4.2_STM32F405_SPEEDYBEEF405MINI_8ce793c1.hex

2.Connect  the drone with the BF,make it enter the DFU mode.

If the BF cannot recognize the DFU mode,please refer: https://docs.speedybee.cn/fpv/fc-flight-controller/flight-controller-faq/connection.html

3.Click "Load Firmware[Local]"

4.Choose the file we download on the first step and click open.

5.Click  "Flash Firmware"