I ran the diagnostics on the laptop and it works fine and had no issues reported. But when i went to use my computer yesterday, all of a sudden there are black squares on the screen and when typing there are lines that fly across the screen. I am guessing the LCD panel is broken? The back area where the computer folds is also hotter than I recall- but that may be because I'm looking for an issue. How do I know if the LCD panel is the issue?

I hooked it up to an external monitor and the squares were still there, but not on the laptop screen when using the program