Hi, this happened to me too and what I did (and it worked) was cutting 2 (or 3 I for got) small pieces of clear shipping tape just about the size (width) of the cable end. Next, tape these on top of the cable end (not the contact side) to make it thicker, then slide it back into the slot. Make sure it goes all the way in, then secure the cable by taping it to the base . Last connect the LCD cable but don't screw it in yet, then lay the LCD and the digitizer down be careful not to make the home button cable move too much. Turn on the iPad to test.
This solution saved me from a night mare when I saw a YouTube video showing that you have to remove the ZIF connector and solder a new one on.