The iPad mini 2 digitizer will not work on the iPad mini 3. The home button hole on the iPad mini 2 digitizer is smaller than that of the iPad mini 3 digitizer. If this wasn't an issue it would work just as good :-/
Make sure the cables aren't getting pinched when you're pressing down. Make sure they are snug nicely under the LCD as much as possible. Also the LCD had 2 black spongy strips on the bottom right and left side. Those are on there with adhesive. Remove those from the LCD. Let me know if that helps.
Guys avoid these problems! Always always disconnect the battery before disconnecting any other cable. As for the the digitizer going crazy after installation always be sure to place a PC of kapton tape over the flex next to the home button. Cover all the exposed chips.
What I have noticed that helps is if you put some black tape on top of this cable line. It helps a little as in like it takes more pressure for it to act crazy. I really think its a bad batch of digitizers. As on some there are no issues at all.