You can tell by looking at the roots. If they have gone brown and soft, there has been damage. First to go is the new roots on the outside, then the old roots near the center, and then the top. That's how a frozen specimen can start to leaf out in spring and then shrivel, the top is still able to function until it needs to make use of the roots.

If you got it in before the roots were killed and it has not gotten too cold where it is being stored it may be in fine shape. You will to keep in a cool, bright area where it does not freeze up hard but it is not warm enough for it to bud out prematurely. If your climate is too hard for it to live outside in the ground you will have to maintain it as a tubbed specimen that is sheltered inside every winter.

As far as plants go, just because there is some root damage, does not mean the plant is a loss. Im assuming as long as 2/3 of the roots are fine, then it should have a decent chance??

Im pretty sure I can get it to survive outside. I just couldnt get it in the ground before we got snow then cold. If its in the basement, at 12C im pretty sure it will end up budding. I dont really have a place that gets cold but doesnt freeze really hard.