iPhone 4s working but blank screen
Hi all, got an iphone 4s which is working but the screen is blank. Put in a new LCD screen but still have the same problem. New dock connector and new battery but still no luck. Drop in a logic board from another iphone 4s, works well. The problem must be with the logic board. What am I looking for or could it be something else? Have restored it with ITunes, no luck.