Filing bug report here on request by Ubuntu bug team, please see discussion on
https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-amdgpu/+bug/1848900

My problem arose after upgrading Ubuntu 19.04 -> 19.10. The lighted welcome
screen displays fine, but when I try to log in I get a black screen and the
monitor appears to be frozen (can't switch to virtual terminal either). The
machine is running normally and I can log on via ssh.

Other users in the above mentioned bug on LP have different variations of the
same problems, some have problems using the live DVD.