Short answer, nothing. I had a Series X in my cart and in the checkout process and the messages kept saying "We're having a system problem but it should be temporary, try back in a little while." Finally, I got an out-of-stock message and my cart was emptied. All this after adding the pre-order to an already populated cart at the moment pre-orders became available. Needless to say, this card-holding, Elite Plus BB customer is not happy. Make me happy again, BB?