Line in middle of screen after drop

I would check the connectors in case they maybe were jarred out of place, but if not then the LCD will need to be replaced. This is not likely going to be a cheap affair given how new the phone is.

Reconnect the screen flex cable or replace a new screen. The cable may loose or the screen is broken.

The same thing happened to me, although all apps are working, my s7 edge ...is flickering all the time... Would that be a sign of a lose flex cable? I tap the back side of my phone, where the flex cable is connected...then the image in my phone's screen changes.

I picked up a MacBook Air on Craigslist for $100 with a dead, swollen battery & horizontal + vertical lines on the screen. Replacing the battery somehow triggered slow, fluttery, goofy booting & a left shift key which doesn't work or uses ALL CAPS which can only be reset with a restart :-/ Upgrading the OS to macOS High Sierra did not help. After a few months, Apple updated macOS High Sierra, which fixed everything except the lines on the screen. I'm happy with this $100 MacBook Air now, lines on the screen included. I wish I only had 1 line on the screen :-)