Do you know how to blindly enter your phones native dialer app? Can give you a dialer code for the maintenance menu and direct you to the screen diagnostic reset if you want to try? Have you tried to restart your phones into recovery mode yet or to download to see if you can see the android pixel display? Might suck but a manual factory reset would fix that issue as long as it's not your hardware. Once on, can you pull down the quick settings menu and see that? What does you carrier say about fixing it?
I had problem, and turn out to the brightness adjustment bar was set all the way down dark. I use the drop down utility menu and adjusted the brightness. The bar is at bottom of pull down menu.