Could it possible have something to do with autorec? Like I state before I am not pointing blame, but I read alot of post where people stated this has happened to them where they used autorec for kitkat and then installed? Maybe there is something where kitkat isnt working well with autorec downgrading the bootloader. If you downgrade any software with a newer upgrade wouldnt that cause instability within the kitkat itself?
What I am thinking is maybe the downgrade of the bootloader is causing over heating since it wasnt made for kitkat? Maybe it sounds stupid but what if? I remember having the black lines happen once before on a gnex I had and if i recall at one time you had to downgrade part of the software to gain custom recovery. My phone in fact got the black lines. What if we find a way to reupgrade the back to kitkats original bootloader and see if that fixes the black lines.
I know there was one case where someone claimed they got it after the OTA for kitkat, but could there be a possiblity that autorec was used in this case also?
I figured I start this possibly here to find a cure for the black lines possibilty. Please delete if not ok here.