Apple is now fixing iPhone 6 Plus touch disease issue which was a huge design flaw by Apple. The issue was a chip (IC chip) which controls the screens touch sensor would fail and the touch sensor on the display would either work intermittently or stop working completely.
There are some guidelines to apples repair program though. Your screen cannot be damaged and of course there cannot be major damage to the phone in general.
You can read more here directly from the Apple website: https://www.apple.com/support/iphone6plus-multitouch/