This happens to me too. Bionic freezes on the splash screen. I can get in via recovery mode but that's it. Also this guy on Ask Ubuntu has a similar Xorg.0.log where at the end the power button, keyboard, and mouse get removed.
https://askubuntu.com/questions/1029384/can-not-start-xorg-after- upgrade-ubuntu-to-18-04 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1756511 Title: Xorg freezes on bionic kernel 4.15.0-12 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1756511/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs