Leap 15.0 froze, cannot login

Who can help?

I was using Libreoffice Impress and the program was struggling when I attempted to insert a video into a slide. Then the screen went black and unresponsive.

I powered off using the keyboard. I can power on and get to the login page, but after I enter the username and password, nothing happens. I’ve tried all 4 defaults in the advanced options, same problem.

The desktop is KDE

How can I take to fix this?