If you put the board in DFU mode, but the configurator is not recognizing it, you may need to update the driver in Windows. This may also help if you select “update firmware” via the FlightOne configurator and nothing happens. This video will help with the process. You will need this program, Zadig, mention in the video.
You may also want to try the Impulse RC Driver fixer with your flight controller plugged into the computer.