Answer to: Touchscreen randomly becomes unresponsiveThe problem of no touch and flickering grey line at the top of the screen is a rampant problem that happens to the six plus. The cumulus chip has an oxidized connection on one or more of the pins and needs to be replaced. I have had four of them now and they all eventually developed this problem. I may learn to do Microsoft micro soldering and go into business fixing them . I think Apple should recall all of them as this is a rampant problem that continues.