I changed everything but the mother board on my iPhone and when I turn it on it gets stuck on the apple logo. I think I may have done something wrong when putting the screen together because when I pull a complete screen assembly off a working iPhone and put it on the one I am repairing, everything works fine. I tried pinpointing the problem to see which part might be not functioning. I pulled the new LCD and put it into a functioning iPhone and it booted up fine. Can it be that the ribbon on the digitizer is messed up? Is my connection faulty?