Chosen Solution
My Iphone 6s plus had this problem where the screen would turn black, but still lit up, if placed in my pocket, and pushing in the screen at the top would allow it to work for awhile again. Recently, however, when I turned it off the screen went completely black (no backlight) and has yet to display again. When I connect my phone to the Itunes it connects right and it receives calls (vibrates for calls) but besides that is completely blacked out and seemingly dead. Is this an LCD problem or logic board issue? Thank you!
You need to rule out a parts problem before moving towards the logic board. I would defiantly try another screen first. If the result is still the same you can move onto the logic board. I would be checking the backlight circuit first. This is not a DIY job and you will most likely have to send or take it to a repair shop for the logic board to be diagnosed and repaired.
