Phone works but Screen is black

Hello!

I have a problem with my Xperia Z3 phone.

Some time ago, I dropped it from less than knee height and when I picked it up the screen was completely black. However, the phone was working, I asked friends to call me and there was no problem, I could even take a picture with the side button(touch screen didn't work).

After searching for solutions I tried hard reset and even ordered a screen and replaced it - still the same problem, backlight lights up, phone works, but screen is black.

If anyone has any idea, I would greatly appreciate it!