Why Enter DFU Mode

I. Detailed Instructions for Entering DFU Mode

• Confirm peripherals have been removed
• Do not power the flight controller with battery or data cable, completely power off the flight controller
• Continuously hold down the BOOT button
• Power the flight controller using a USB data cable
• Release the BOOT button
• Click "I have entered DFU mode"
• Click Start Connection
  

Important

If you still cannot successfully flash the firmware, connect the flight controller to the computer's INAV ground control station, repeat the above steps, and check if DFU mode has been entered
How to update the flight controller firmware - using INAV ground control station: https://docs.corewing.com/plane/beforetuning/inav-fw-update.html

II. What is DFU Mode

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