Touchscreen not responding, even after LCD/Touch replacement OEM

So i have encountered some issues with iPhone 6 and iPhone 6 Plus.

The touchscreen will freeze and to me make it work again i need to restart the phone, i thought the issue will get fixed replacing the LCD/Touchscreen assembly. But it persists. The chasis was a little bent and also thought this is causing this issue, but even after straighten the issue persists.

What i have done and haven't fixed my issue:

1. Replacing the LCD/Touchscreen assembly (aftermarket)
2. Swapping the LCD/Touchscreen assembly from a functioning iPhone 6 to this one
3. Straighten the chasis
4. Have the inner chasis covered with thermal tape
5. Restoring the the iOS

Does anyone have encountered this issue? And knows how to fix it?

Thanks!