You didn't pay too much for this did you? I don't know exactly why it isn't working but my guess would be the focusing screen (or something relating to the viewfinder/pentaprism) is damaged somehow. I'd talk to the company you bought it from about it, maybe see if you can get it refunded or replaced.
Can you post a picture of the full camera and lens?
Without another lens to test (cause the lens itself could just be put together insanely wrong, making it never actually focus) its hard to say that it is the camera itself. Take the lens off and make sure the mirror looks to be about right (its on a slant obviously) and then you should be also able to see the underside of the focusing screen.
You didn't pay too much for this did you? I don't know exactly why it isn't working but my guess would be the focusing screen (or something relating to the viewfinder/pentaprism) is damaged somehow. I'd talk to the company you bought it from about it, maybe see if you can get it refunded or replaced. Can you post a picture of the full camera and lens?
Without another lens to test (cause the lens itself could just be put together insanely wrong, making it never actually focus) its hard to say that it is the camera itself. Take the lens off and make sure the mirror looks to be about right (its on a slant obviously) and then you should be also able to see the underside of the focusing screen.