Buttons T, G, V not working on iPhone 6 keyboard

Hi,

I'm facing an issue with the keys T, G and V that doesn't respond on the iPhone 6 keyboard.

Mention that I was searching all the forums and follow all the recommendations, but i still have this issue.

I was installing an application (Touch Test) that is checking almost everything about the display and find out that a full vertical portion of the screen is unresponsive.

See attached pic (white dots are the un-responsive ones).

Anything what comes in this white dots area is not responding on the touch screen, even the sliding bar for powering off the mobile is not responsive.

I was checking the ribbon cables inside and looks without any visible damages.

What you will recommend in this case?

Could be repaired or have to go for full touchscreen replacement?

Thanks and awaiting an answer.