Touch is not working

Hello.

I recently had a customer come in with a broken screen where it displayed image just fine, but the touch was not working anywhere on the screen. So naturally i assumed replacing the screen would do the trick. But still after replacing the screen the touch still don’t work. Image displays fine.

I know there is a small chance the screen i received is defective but it seems more likely to be something else. I have ordered a new screen to test it but in the meantime i was hoping maybe anyone got any suggestion for where to look?

I am not very familiar with the iPhone XS Max motherboard and i can’t seem to get the schematics for it yet.