Some may say: Don't fix it if it ain't broken. I say explore everything in life. So; as the curious guy I am I had to remove every screw and every component from my iPhone
So, I didn't read the guides clearly, and aspecially one step that told me to be extra carefull with the ribbon cables as I put the display back on. This resulted in an unworking touch screen
READ the guides before starting to repair - completely! Make sure you know what to look out for and do not be in a hurry!