Was just talking to my local shop about trading this in against something that’s come up there. They’d sell it for £230 so my pricing here of £199 is decent.
It should automatically switch to interface mode as soon as you plug the USB cable into the computer.
While powered on, you could long press the button to perform a factory reset.
Are you using the USB cable that came with it?
Do you have a chrome browser open at the same time? Chrome will hog the MIDI connection as windows only allows one usb MIDI device at a time. Close down anything else that uses usb MIDI.