Ghost touching, flickering and self use

Sorry for the late reply.
It seems you are experiencing an array of the following issues:

https://forum.fairphone.com/t/screen-flickers-at-low-brightness/11577?u=paulakreuzer

and "shut down during calls I guess is one of these:

Please read these topics for workarounds & tips and continue there if you have further questions.
Also a software update is currently being tested which tries to fix some of these issues. You can apply here:

Oh and about not being able to take off the screen, take a look at this topic: