Iphone 7 plus black screen but still on

[blueridge]

my iphone 7 plus was working fine then after this latest iOS update it went to a black screen but i can still get calls and texts notifications sounds. It will make the sound when you put your finger over the home button. I tried to hold down power and volume down but nothing changes. I had a guy look at it and he tried 2 screens and new charge ports but it did the same thing. He said the backlight is still on but the screen is black. he said it looked brand new inside no physical damage to any chips that he can see and no water damage.. the phone has been in a case since i bought it and never dropped. I hooked it up to itunes and i can see it. Any ideas? of course its out of warranty..

Thanks in advance