Laptop freezes with Green and purple screen

[GamingLaptop20]

Hi I have a gaming Laptop which is about 4 years old. Since yesterday it has started freezing randomly (while playing game, on Google chrome etc) with this weird purple and green screen overlay. The screen brightness also brightens by itself until the screen is completely white, then go back to normal and either repeats this in an infinite loop or goes back to normal and I can use the pc again for a short while until it does it again. Sometimes even when I turn it on and off it won’t even boot up the dell logo and go to the lock screen as it will be stuck with purple and green. I really need this laptop for uni. Can it be fixed? Thanks 

(I’ve attached some pictures as I’m not totally sure how to correctly explain it)