So, here's the thing, after 2-3 days upgrading to ios 6.1,i encountered a serious bug. (or maybe my iPad ids defective idk) Whenever i try to unlock the ipad,the screen will dim and m ipad will froze for like a minute and then restarted. I have restore the ipad by going to dfu mode and connect to itunes but to no avail. The problem still persist and i can't use the ipad at all. Is this a hardware problem? If it matters, i'm using iPad 2 16gb wifi. Help anyone?

Suspected Hardware, as you already tried reset it back right?

Yup,fully restore it via itunes and still no success. My friends said it's Nand problem.

Try restore your iPad iOS again and set it as a new iPad instead of restoring the backup settings

Tried already. Still didnt work

Since you have restored and the problem still persist, sounds like a hardware defects then.