I'd bet it is the screen. See at the samples of broken screens of M92 here:
http://onyx-ereader.pl//files/0000/0122/EkUszMech.jpg
I had very simmilar failure. It appears that the screen is very fragile and not flexible at all (it is on glass). Little bend was everything, that broke mine.
If I knew about that fragility, I'd reconsider buying at.
Replacing the screen is not much work, but the screen itself is fairly expensive.