Looking again at your screenshot I can see what the problem is.
It looks similair to my phone when I have the cover on it (S view)
It look like this:
My guess is that you have a hardware failure. It looks like the sensor that triggers it mailfunctions. Also I think that the digitzer is broken. I don't think it happenend after a flash, seems really unlikely.
Sounds more like just failing hardware or maybe even water damage.
Originally Posted by trein91
EDIT: Btw, when I'm on touchwiz, It shows the "select language" page for a split second, before showing the black screen with the clock widget.