Hi Rune
The doorstone at Newgrange is fixed open and never gets shut. It is not carved. When the entrance was first found the door had fallen forward onto the back of the entrance stone and, as far as I know, it remained there until the renovation. It may have been shut during excavation to make sure it fitted, but that would be about it. I'll take a look in the excavation report when I have a mo and see exactly what's said about it.