I asked her to ctrl+alt+f2 and execute these commands:
sudo apt-get update
sudo apt-get upgrade
> Didn't fix the issue.
Asked to do this: sudo apt-get install --fix-missing
> Nothing.
Asked to do this: sudo apt-get install gnome-shell
> Nothing.
Asked her to write this: startx
> She reports some screen blinking and restart-sort-of-thing that ends with black screen and cursor.
Asked to write this: cat /var/log/Xorg.0.log
Here's some more photos she made:
At that point I ran out of ideas. These days it sucks to be Linux user. I can't believe they haven't developed some automated fallback or recovery method yet, it's about time. Even Windows has safe mode.
edit:
images are now shown in this post directly.