iPhone letters don't work

The letters on an iPhone 6 device do not work. In this video we are going to diagnose and repair step by step, this failure of the touch screen, when some letters stop working.
MOBILE REPAIR COURSE 16
In this case, the right column has stopped working: the letter Q, A, Uppercase and Numbers. For this repair we need to measure the impedances of the FPC connector of the touch screen and find the culprit.