Umm to be frank, nokia would most likely never have its production base in North Korea. Neither would North Korea would have that much technological advances to be able to make something as delicate as N900. I would vouch that N900 are made in South Korea, not North Korea.

There aren't that many options viable if the situation is a hardware problem. There's no real software that can solve hardware issue especially when most of the inner workings of devices like these are namely proprietary (which information on how they specifically work cannot be easily obtained by the public).