I had the common login loop problem, after debugging it’s a bug due to nvidia driver itself,
I tried a couple of fixes, but no hope, till the machine (4x gtx 1080 Ti) had a complete failure, after removing the nvidia drivers then installing it as part of the solution.
In order to operate the machine now, I had to:
1- Enter the machine in recovery mode
2- Choose the root option
3- Remount the disk in read write mode
4- Exit this root mode
5- Choose continue to normal running
6- Enter the encryption password
7- run: sudo init 3
8- Now I have a simple GUI
9- Edit DNS records so I can connect to the Internet.
Now, I really wanna restore the normal GUI and login to the system.