Touch not working after writing screen data

First iPhone XS Max I received with damage in the display. The left corner was black and the rest works fine. Looks like it only cracked a little. The customer wanted to replace it because it cracked where you read the time xD. We have a DEMO model we only use for showing customers so I thought might as well swap displays..

I copied the display info and wrote it on our display but the touchscreen didn’t work. When I put back his broken display it works just fine.

I put back the original information on our display and the touch still doesn’t work on our DEMO model. I read online that this is a known problem when replacing XS displays but this is the original display.

Did I break our display or did it happen because I replaced the serial. I wrote back the original info. When I read the diaplsy it shows the original information.

Was a tear in 1 of the flex cable where the strip of adhesive is. Was so small it was barely noticable. Changed another display and It works now. Might have accidently damaged it when taking of the display. Whoops