1. Detailed Instructions for Entering DFU Mode

• Ensure that all peripherals are removed.
• Do not power the flight controller using the battery or data cable; completely power off the flight controller.
• Press and hold the BOOT button.
• Connect the flight controller to power using a USB data cable.
• Release the BOOT button.
• Click "I have entered DFU"
• Click "Start Connection."

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If the firmware still cannot be successfully flashed, connect the flight controller to the computer using the INAV ground station, repeat the above steps, and check whether it has entered DFU mode.

How to update the flight controller firmware using the INAV ground station: https://support.speedybee.cn/?s=teched&t=a&p=115&i=91442261866319872

2. What is DFU Mode?

DFU = Device Firmware Upgrade

DFU is a built-in boot mechanism (ROM Bootloader) for STM32 series microcontrollers. It does not rely on the main firmware, and as long as the chip itself is not damaged, the firmware can be flashed or repaired through DFU mode.