Only upper part of the replaced screen is responsive to touch

Replaced the screen as per IFIXIT instructions. I need to enter phone PIN number on startup. I can only enter the digits 1, 2 and 3. The screen is unresponsive to anything below where these digits are displayed. I can't select 'cancel', 'delete' or any other digit on the screen. I had to put the cracked screen back and everything on the old screen works apart from the cracked glass. Is this an indication that the replacement part is faulty?
The cables connecting the display to the body appear to be fixed in place. They are not loose so I think they are fully seated.