V3 hub instance still booting 20 min later

I wanted to try out the Hub, and saw that a v3 version for the robot was available. So I selected that and it put up a message saying " Booting Server (Please note: this can take several minutes)". But 20 minutes later it’s still booting. No big deal, but there seems to be no way to cancel it and go boot a v2 instance. Any suggestions?