Brad makes a good point about selling it yourself if you don't want to keep it. First, though, ...
I would wait and see what the seller says. If he/she cares about his/her reputation (i.e., feedback rating) on Ebay he/she might allow you to send it back for a refund. Offer to pay all of the shipping costs, the Ebay listing fee and the re-listing fee (assuming they'll try to sell it again). Although sellers on Ebay who don't clearly describe the shortcomings of an item may not technically be doing anything wrong, it's not considered ethical to do what you're describing happened (i.e., leaving out blatent shortcomings of an item, or not telling you that the item is not the current model). If you don't care about your own feedback rating (doesn't sound like you'll be participating in a lot more auctions), tell the seller that you'll be forced to leave negative feedback if a refund is not provided given that they omitted a major shortcoming of the unit and did not make it clear that it was not the current model. (Can't believe they tried to pass off such an old model as brand new.)