Best Buy Reward Certificates question

[N8 Storm]

I purchased a big ticket item that I ended up returning due to a defect the other day. I don't think my credit card has been credited back yet, but will be in the next day or two. Not sure if I should have, but I did however use the reward certificate that I am guessing I most likely got due to said purchase for some blu-rays today. How does that work as far as my reward program/Best Buy credit card goes? Will I still be refunded the full amount for the returned item, but it will take me a longer time to build up to my next reward certificate since I may end up being in the hole as far as the rewards program is concerned? Or something else?