I had an iPhone 5S that I changed the screen on, due to water damage - the screen I bought was also apparently a genuine Apple item and I had no reason to dis-believe this. Everything worked on the phone apart from the prox sensor that turns the screen off when it's against your face. Reading through these sorts of forums, I doubted the screen and tried various fixes without any success. I then bought a new £5 front camera, loom and sensors and they worked straight away. Moral? It's not always the screen! And next time, buy the pre-assembled one which had all the parts on but was £50 and not £25. Would have saved me a lot of time and grief in hindsight.
