I have a 6plus and suddenly last night the phone wouldn't work. There was a fluttering white line across the top of screen. Hit buttons and something different would happen. Even had trouble shutting phone down. Battery as of late been dieing fast. Someone told me they had same problem....needed new phone!!! HELP
That screen issue occurs when the internal touch screen unit is separating from the device's motherboard. The most common causes of that separation issue is due to the dropping or bending of the phone. If you selected an AppleCare coverage plan that's still active an Apple store can replace the touchscreen for you to fix it. Or they could advise you of their repair charges for fixing that if it's out of warranty.