Why is it stuck in boot loop?

I did a screen replacement on a Boost Maxx and the new part I ordered was the screen assembly with frame. So basically I just swapped out the guts. Now when finished it powers on and shows the white ZTE android Logo screen and then shuts off and does the same thing over and over. I unplugged the cable that connects the vibrator and speaker on the bottom and it will boot up fine. So i ordered a replacement cable. Replaced it and now it's doing the exact same thing. I'm up against a wall. Not sure what else could be the problem. Any help would be GREATLY Appreciated!