2 Replacement Screens, Unresponsive in same place on both screens

i had a damaged iPhone 6 screen (cracked) that i figured id repair now that i bought myself the X, the issue is, after replacing the screen, i found that there was a dead section running vertically from top to bottom in the middle of the screen,(if you pull your keyboard up on your phone, this line of unresponsivenes runs over the b key from top to bottom)

anyway i figured it may have been a dud screen, so instead of transferring components, i bought an entire replacement front assembly from a different manufacturer (camera, screen, digitizer etc etc.) and just swapped the home button to retain touch id.

however i found i had the same issue, and these are the steps i have taken to rectify

1) Put device in DFU mode and restored firmware from a fresh download

2) clean ribbon cable sockets and cables with isopropyl alcohol

3) replaced the screen again (obviously!)

4) hard and soft resets

5) reseating cables

any recommendations to fix, would be some handy cash if i could fix and sell