Wont boot up because of the front facing camera

Hello, i have just completed my first iphone 7 screen replacement. I have repaired hundreds of other iphones but this is my first try on the 7.

Everything went really smooth during the repair until i turned it on.

Apple logo, for a really long time. Then it shuts off and starts again. The sweat started thrilling down my forehead, and i got a mini heart-attack. Because this has happened before, and it has been motherboard related all the times, so i was really scared.

Checked with the old screen and now it powers on just fine. Woah, what a relief. I try the new screen again without connecting the front facing camera, and it boots up just fine. The front facing camera flex is the original and it hasnt been replaced. Doen't it not power on because the flex is broke or something? Anyone experienced this before?

Thanks alot!!