Frozen on restart screen

I was playing around with Umbrel, and decided to restart it because the app downloads had frozen. Now it’s been on the same screen, Restarting… Please don’t refresh this tab or turn off your Umbrel while it is restarting.
If I open a new tab, Umbrel is unreachable.
So it has turned Umbrel off (but not the pc running it), but not started it up again. What should I do?