Touchscreen problems are affecting the Apple iPhone 6 and iPhone 6 Plus
According to smartphone repair chain iFixit, older Apple iPhone 6 and Apple iPhone 6 Plus units are being hit with a problem that Apple is aware of, but refuses to consider an issue. You can read all about it on Apple's support forum where there are a number of complaints about an unresponsive touchscreen, accompanied by a horizontal flickering gray bar at the top of the screen.
While Apple employees are familiar with the problem, a number of them have told owners of an affected device that Apple does not recognize the touchscreen problem as an issue. If your warranty has expired, as is quite likely, Apple will tell you that your only option is to buy a new phone.
"The issue is ridiculously widespread and Apple should’ve issued a recall or maybe a free warranty repair on this problem already. If you own an iPhone 6+ and haven’t experienced the problem yet, then I think the chances are pretty high that you’ll experience it during the lifetime of the phone."-Michael Huie, repair specialist
Twisting the phone, or pushing on the screen, will provide some temporary relief. But the disease comes back, hitting even harder than before with the gray bar covering more real estate on the screen. The display then gets worse and worse until it doesn't work at all. Replacing the screen also provides only a short term fix. Eventually, the gray bar reappears on the new screen.
Theories as to the cause of the problem have been narrowed down by most repair pros to two. One theory is the U2402 Meson Touch IC chip has a manufacturing defect. The other possibility has to do with bendgate. As the phone naturally bends, solder balls used on the motherboard start to crack and lose contact with the board. This prevents touch inputs from turning into the signals required to make the touchscreen work properly.
Most of the things that an iPhone 6 or iPhone 6 Plus owner can do to repair the issue are expensive. Buying a new phone or replacing the motherboard both come with a high price tag. It is less costly to replace the IC chips. The suggestions made by iFixit are pretty clear cut. If you still have a valid warranty, use it. If you're out of warranty, go to a repair center that handles board-level repairs and have them replace the two Touch IC chips. This could be done for less than the price of a new iPhone. And some repair centers will also reinforce the motherboard to prevent them from flexing.
source: AppleSupportForum, iFixit via Forbes
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