My phone screen decided it randomly wanted to burn out, so I guess I need a new one. It works for…

My phone screen decided it randomly wanted to burn out, so I guess I need a new one. It works for about 30 seconds and then the screen shuts off and won't come back on. When it does come back on, it slowly gets duller and duller until it's black. 😔 Wtf dude. It happened out of the blue! I didn't drop it, didn't get it wet, it didn't overheat...just random...I'm sad. I'm using my boyfriends old phone now but it only works on Wi-Fi because it's a sprint exclusive and I have at&t. meh. Hopefully I get something figured out...I don't wanna be stuck out somewhere and not have any service.