If these steps do not work you can try using dr.fone - iOS System Recovery with no data loss: https://goo.gl/uLbdyP

I give you three easy possible solutions to get your Iphone 6S / 6S Plus display working again. This will work for many of you especially if you can feel your phone vibrate or hear any ringing or sounds. Good Luck!

Option 1: Hold down home and power button simultaneously until you see the Apple logo.
Option 2: Hold down power button for 3 seconds then hold down the home button until Apple logo appears.
Option 3: Firmly press directly under your flashlight and camera lens as your back light display connector may have gotten dislodged.

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