My guess is that it’s an ESC setting issue. You should connect to your ESC via blheli suite and make sure all 4 ESC have the same settings/timings etc as my guess is that ESC of the faulty motor has some strange setting on it. You also might as well update the firmware on all 4 of your esc. Worst case if all the setting among your ESC are the same and it’s just that motor at fault you will need to replace the ESC.
I just found out one of the motor won’t work because of the poor connection with bad soldering. I re soldered the wire and now all four spinning in the same speed. However, when I plug in the usb to the fc it no longer gives me the beeping sound(it used to beep when usb plugged in) and when I tried to calibrate it, it has no sound at all.
Sometimes its best to try restart your PC… but if you still having issues after that (and you have tried to reinstall your drivers and reflash firmware) then maybe your FC is dead 