I've upgraded openSUSE Leap 42.3 to 15.0 on my laptop.
After the upgrade, if I choose to shut down Plasma session either with logout
command or by killing XOrg, the screen goes dark and computer stops responding
keyboard commands.

I use 'modesetting' xorg driver. If I install the xf86-video-intel driver, the
screen goes dark even before that, while logging into KDE.

The GPU is 2nd gen sandybridge. I'm not sure what other info I can provide.
It's possible to ssh into computer while the screen is dark.