I want to reflash the ArduPilot (using STM32CubeProgrammer) and configure it from scratch. I can’t enter DFU mode. It’s always worked, even with the modules connected (GPS and ELRS), by holding the BOOT button. Now, even with the modules disconnected, it doesn’t work. Windows sees it as an “Unknown USB Device” (device descriptor request failed). When I start the FC normally (without holding BOOT), ArduPilot starts normally and works, the problem is only with entering DFU mode (it worked correctly before).
Try other cable
I tried several cables when this problem occurred, but this time I used a very short cable and it works. Thanks.
If that’s the case you don’t need to be in DFU mode to flash Ardupilot again. Download the ..apj file of the version you want from the repository and use Mission Planners’s Load Custom Firmware to flash it.
Stable version of Copter for example found here
SpeedyBee F4V4