My iPhone 6 has gone black after dropping it, HELP!

I dropped my phone yesterday and the screen shut off, there's no damage at all to the screen. I opened up my phone and checked that the screen and battery flex cables were fully secure which they were. I also tried holding the home and button down for 30 secs and restoring via iTunes as the phone did show up on my computer. I don't know what else to do, I asked apple but they'd charge me £136 to fix but I don't want to be spending that sort of money on it.

Any ideas??