Currently I have a non-functioning machine due to an Ubuntu update.
I updated my nvidia-display driver, I ran sudo apt update, and then I rebooted.
Now I can't enter UEFI, the grub boot menu or Ubuntu 18.04.
After boot I get the following screen. This screen loops with a black screen.
I can run Ctrl+Alt+F2 to get a terminal, which gives the following screen. This screen also loops with a black screen.
This console doesn't look like Ubuntu, however Katoolin did this to Ubuntu 18.04 and the question is how to undo it.
I have a dual boot of Ubuntu 18.04 and Windows 10. On Ubuntu Katoolin is installed. Probably this explains the image shown in the second screen photo since I have two OSs installed in some sense.
My GPU is Nvidia RTX 2080Ti and I have an PCI-E wireless ethernet adapter installed.