After the last print something really strange happend.

There was 49 min left on the last print, I went out for a bit and after I returned the print finished but there was two black bars on the screen.

The buttons made sounds when pressed, and the printer was functioning as far as I can tell by the sound it made when pressing home. I reflashed the firmware, and after the printer restarted after the reflash, made all the correct beeps, except, the LED did not come on, and the two black bars persists.

What can be the problem?

Thanks in advance for any help