Chosen Solution
Hi I have a cracked display not original which started to be unresponsive at the bottom part of the screen. So I bought the LCD from IfixIt and changed it. But now it loops the start up Apple logo and nothing else. The old screen works okay as before when I change it back. Could there be any issues with the new screen and other parts like the home button, which is not original?
Try to disconnect the front cam and proximity flex and start up your iPhone
It could be the screen itself. It could be the home button cable or the home button itself. And in case you purchased a full assembly with small parts, it could be the front cam assembly as well like Ron Schuts suggested. Can you isolate by connecting only the two cables: LCD cable and Digitizer cable, and see what happens? Note that continuous boot looping will eventually corrupt your data permanently. Save a back-up using your beat-up screen first, then proceed with any testing you want.
I haven’t had that happen before if might be an idea to contact apple. The only thing i could think of is Apple brought an update being if you had to replace something it had to be from an Apple approved dealer or Apple. But im not sure if you could give more detail i could maybe give you a better answer
