I think restoring the phone fixes the issue.

I have also an Iphone 11 after I replaced the screen and battery it keeps restarting even if I only connect screen and battery without the other flex cables. I’m suspecting the screen I will buy a new Iphone 11 screen and a new battery to test. Note I have tested another motherbaord and it keeps restarting. And I’ve tested another battery and it keeps restarting I have tested with Iphone xr screen and it keeps restarting The only conclusion for me here is that I’ve been so unlucky and all those screens and batteries are faulty (or non compatible) I will let you know if I find a solution.