Black screen Galaxy Book Pro NP950XDB

When I power up a screen comes up which allows me to enter my pin number. When I enter the last number of my pin two things can happen:

1. It immediately goes black, or;
2. It goes to a welcome screen with the rotating dots for a few seconds, then goes black.

I go to task master using control, alt, delete which shows no programs running. When I close the task master the screen is still black. I have three “users” on the computer and the same happens with all three. Battery is fully charged. Computer shows it is WiFi connected. I can shut down and restart with background, time and date showing. When I hit enter the pin login screen appears. No mater which user I select it shows “Welcome” for a second then a black screen. I have a mouse connected with a dongle and the cursor moves correctly on the screen regardless whether I use the mouse or mouse pad on the keyboard.