Chosen Solution
My iPhone 6 screen recently went black. The history: The screen and battery have both been replaced in the past. A gap appeared in the top left hand corner of the screen and eventually the screen went black. The phone was very hot! I changed the battery again because I thought that might solve the problem, but no. Now, when I connect to iTunes it recognises the phone and says it is locked with a passcode. I have tried another screen but this doesn’t work either. Is the logic board fried?
Sounds like backlight blown from a bad quality screen. Check if you can see dim image display on the screen with the use of a flashlight on the screen. Usually I test this when the phone is turning on so use home by and power btn for 10 secs and turn on phone again then look for dim apple logo.
