Blue screen while logging out/going in to lockdown mode - system inaccessible

While switching between normal/lockdown mode in trying to debug an issue with Chrome not being able to load a tab, my system (Surface Pro 4) blue screened in a driver. I don't recall the name exactly, unfortunately (it was a name that started with w, had 'bem'? or 'bd' and a number following this, with a .sys extension). IIRC it might have been a keyboard driver based on what I recall of the name.

In any case, something got messed up by the crash so that now, after restarting, Windows 10 (64 bit, Pro) shows the login screen where I have the option of logging by clicking a button (removed my password temporarily for the (only) admin user) which, when I press results in a black screen where I see the mouse cursor but nothing else. At this point, I can hit ctrl-alt-del and get to a blue screen which has the option to switch users (unfortunately no other ones are defined), and shut down/restart.

My system being a Surface, getting to the repair screen during boot-up is kind of a pain, but I can do so after a few failed Windows restarts. I can get to a command prompt where I was hoping that you could tell me what registry key I could modify to get out of lockdown mode.

You won't be able to disable Secure Lockdown with modifying a registry setting. Your best bet at this point is to restore to a previous restore point if possible.

I'm not sure I can restore since I can't get into Windows. You might want to consider some way of turning off lockdown mode in this type of event. IMO, this crash was caused by Secure Lockdown and whatever it does when switching to lockdown mode

What we suggest (which is highlighted in the User Guide) is to create a second administrative account on the locked down system. The will allow an admin to delete the locked down account and recreate it.