Gnome Tweaks change of caps lock to control caused lock out of the system

I have a brand new Purism laptop (Librem 15 version 3) with PureOS I started up for the first time today. While setting it up to my liking, I opened Gnome Tweaks to change the Caps Lock button to be a Control key. Immediately upon changing the setting (without any other action on my part), the system locked the screen and any further efforts to log in result in the screen going blank momentarily and the lock screen being displayed. Unsurprisingly, this makes the laptop unusable. There's no bug report regarding this . I was unable to usefully identify the laptop based on the information at wiki.puri.sm/hw . I consulted my order information instead. It doesn't appear to boot grub, but I'm not sure I'd know. I can reach the BIOS settings, but nothing there seems to do anything useful. As to rebooting, I did try that immediately. No change. I can log in using Ctrl+Alt+F3, as suggest, but there's no server running a display at that point. I'll be awaiting a response from Purism before I wipe my user configuration.