Mike Anaya, my iPhone7 is doing the exact same thing. When it does manage to boot (the logic board gets almost too hot to touch at times) it will randomly freeze. I can play a game for example (once it finally opens) and no problems. Camera does not work, It is black with what appear to be a far left and far right single pixel wide columns that seem to show that part of the image. But usually locks up.
Phone worked fine with 10.3.3. Was not until 11 that these issues appeared.
Now I am using 3rd party software to see if going back to 10.3.3 will help. Otherwise there is something in the logic board. Will followup if success with 10.3.3.