iPhone 6 Plus Digitizer issues

I run a side business repairing iPhones doing anything that don't require micro soldering. My skill level is pretty extensive as to understanding of the board and etc. just don't have the equipment to properly repair micro soldering jobs.

I've came across what I accessed as a simple job.

Client stated that screen was busted just needed a replacement.

I did the repair and a few hours later client states that phone is being unresponsive to touch at times.

I checked the phone too make sure the flex cables wasn't bent or tore. Also disconnected the cables and reconnected to under proper seating of the flex cables.

Phone works fine for awhile but then starts to act up again by not being able to touch anything after a few power on and offs it became responsive again but shortly after it yet again acts up.

I push at the top right hand corner of the screen and it makes it work again sometimes. So I got another screen and tried it. Same problem. Another screen to be %#*@ sure it wasn't the screen. Again it acts up.

Tried 3 screens and problem was present in all 3 screens, mind you they was from the same supplier what's the chances of all 3 screens doing the same thing? I use cellphoneage.com for my screens and of all my time doing tons of repairs I've never had this problem. I've cleaned the digitizer connector with alachol and a small brush. Nothing helped.

I attempted to put a piece of paper on top of the connector before I put the plate on to insure a solid connection and it actually helped to some extent. Although it wasn't a 100% fix because it would still sometimes act up.

I inspected the digitizer connector on the board to make sure there was no damage there and all the connectors are there and no damage seen.

I'm thinking maybe it need a new connector on the board to the digitizer. despite the good shape connector, also in not sure if this problem was preset before my repair.

Any ideas?