Repaired digitizer, and now the iPad won't turn on.

Hi, everyone.

So i replaced the digitizers on two iPad mini 3's. One was just a mini 3 , and the other was the kind with the finger print. The fingerprint version is up and running with no issues, the regular mini 3 will not boot up however. This is not a darkened LCD issue. the unit will not power up or charge, and doesn't show up when attached to my laptop. i have left the battery unplugged for over 5 minutes and tried everything i can think of to no avail. hoping someone has some trouble shooting tips to help me out. i do have a multi meter so checking values on components shouldn't be too difficult. i just don't know where to look, or what to look for. thanks in advanced for any help

best regards, Tim Misnik