A friend of mine who owns an iPhone 6s (with a replacement screen as she dropped her phone a while back) updated her phone to iOS 11 and the screen stopped working as well. I did DFU reset and it doesn't work as iTunes would restore the phone with iOS 11. So I downloaded iOS 10.3.3. and restore it using that, and the screen works again! I guess from all the answers I've read, iOS 11 doesn't work with a non-original iPhone screen, your best bet is to downgrade to iOS 10. Hope that helps!