Hmm, interesting. That tells us that it’s not actually a problem with your graphics driver or kernel version, and given that it was working on this version before, I would think some aspect of Xorg configuration, your graphics hardware has an issue, or your installation in general has been corrupted when it tried to upgrade.

You might try to detect corruption by using a tool like debsums to check for any obviously corrupted files.

What’s the state of your debian packages I wonder… does something like apt-get update or apt-get check highlight any problems with the state of installed packages that could point to a failed upgrade?