Damn, that sucks. Really, your situation is the ones I hate most in these poorly supplied inventory situations, as those who may have really wanted a mini for the holidays, or an NS at launch, finally get it, only to be defective, with little to no other options for a replacement. I would hate to see this for a child on Christmas, but I guess shit happens.
Inventory has been in the most supply this week, then at any other time, so maybe call around to other stores in your area, and explain you have a defective unit that needs to be exchanged, and if any places have one, they should hold it for you since it's a replacement. You could also try and call a district manager and talk to him directly, as he may be able to produce one for you as an exchange.
The worse case, just contact "N" and have them fix it. It may take a week or two, but at least you'll have it. If this whole situation has rubbed you the wrong way(which it would have for me), just say

it, and return it outright.