What does locking the root password do?

[Jt0]

For reference, I was able to unlock the root password in the QEMU image:

QEMU root password

I might just be missing this part of the documentation, but I’d like to use a shell as the root user in the Librem 5 QEMU image using the most recent version uploaded (build 4204) and can’t figure out how to become root. I’ve searched the documentation and the forum and can’t seem to find it anywhere, and “123456” doesn’t work. What’s the password?