Dropped iPhone6, no screen, sound or vibration. itunes restore success

This is a belated answer so hopefully it can be of use to folks who search for and find this question.

There are several issues here and it's hard to say of they are all related or not. The first thing that has to be determined is whether the screen problem is logic board related or not. Trying a new or known-good replacement screen will help here. If the replacement screen doesn't work, then the next step is to see if the problem is backlight or LCD related. Shining a bright light on the screen when it is connected to iTunes will either reveal a dim image (backlight issue) or no image at all.

At that point, you start getting into a more serious board-level troubleshooting and repair and is best left to a repair shop that does micro-soldering repairs.