MCU not responding to anything

hello, i am having the same issues and am a complete noob. what do you mean get the correct path? i unplugged the board and used the sudo dmesg but a lot of information pops up. i did have the bullseye bug but i believe it was remedied after following the steps you have posted on a forum. i still get
Failed to flash to /dev/ttyACM1: Unable to find serial ‘by-path’ folder

If the device is already in bootloader mode it can be flashed with the
following command:
make flash FLASH_DEVICE=1eaf:0003
make flash FLASH_DEVICE=1209:beba

If attempting to flash via 3.3V serial, then use:
make serialflash FLASH_DEVICE=/dev/ttyACM1

make: *** [src/stm32/Makefile:111: flash] Error 255

any help would be appreciated!