After replacing LCD, Inverted colors and unresponsive touch.

Hello,

I recently replaced the LCD and Digitizer on my iPhone 6. On reassembly of the product i found that the screens colors were inverted and in negative form. also the touch on the digitizer was unresponsive. I did some further investigation as i believe it may be the a faulty screen or the plugs not inserted correctly. I tried another screen to rule out the LCD been the issue.

I have found that if i don't plug in the digitizer and only the LCD the colors are fine. soon as i plug the digitizer in the colors change to negative. Could this be a software fault or a fault on the FPC for the digitizer. The phone has not been dropped either.

Appreciate any help you can give

Best regards

Carl