I'm playing around with the STM32F407VE devloppement board, but I've noticed a very strange behaviour. When the board is in DFU mode, it appears in the USB peripheral folder in the peripheral manager. When I try to flash directly with Arduino IDE or PlatformIO, I get a "no COM port detected" error. Yet, STM32CubeProgrammer works nicely, so it didn't matter too much. Now I've just flashed a I2C adress scanner on the board, which should report the adress over the serial monitor. But when I plug the board to my computer, nothing happens. No notification, no sound, nothing in the COM and LPT folder, or in any other folder for that matter.
I've tried to compile the code with the "STM32F407V series" core in ArduinoIDE and with PlatformIO's STM32F407VE environnement. It didn't change anything. I've also installed all the drivers I could find, I tried on another computer running Linux Mint, and it just doesn't work. I find it really weird, especially knowing that communication with the bootloader does work fine.
EDIT: I tried to use my STLink to debug. I powered the board only with the probe's 3.3V and the processor quickly started to heat up (I checked multiple times the connections, they are correctly made). I disconnected everything and tried removing the 3.3V and powering the board from it's USB port. I never got the stlink working, it would not detect the board. I then tried to upload a new code and even though my computer would still detect the device as STM32 BOOTLOADER, STM32CubeProgrammer was not able to connect and to flash the code. So I guess something went wrong with the stlink and it fried something.