Thank you for your feedback and for playing!! We sadly noticed too late, that the arrow buttons were too small and that we forgot to add some sort of feedback to them. We want to update the game after the jam to fix things like that :)
You can turn off the PC via the power button, but only before your computer gets taken over by whoever or whatever takes control over it and you have to unplug it. But before that, you technically can turn it off normally :)