Best Buy Open Box Alienware unable to be registered by me

Hello!

A friend of mine just bought for me, during a trip to the US, an open box Alienware 15r3. I live in Brazil.
I've tried to register it to myself, but it seems the previous owner had already done it.

I've been bouncing back and forth with Alienware and Best Buy twitter accounts, but no resolution so far.

I have the receipt with me.
How can I do this transfer properly?

Please help! :)