To rid an offensive odor?

I find thermoelectric wine coolers at my local thrift store from time to time and have had great luck with them. I recently found a used 8 bottle Emmerson unit that looks a heck of a lot like my Vinotemp. I picked it up for a decent price but it was a little abused. After wiping it down well with water I scrubbed it with baking soda and then cleaned the baking soda off as well. I now have it plugged in and running with an opened box of fresh baking soda in it. I can still smell something which reminds me a little of mustard in it though. Any ideas of how I can rid myself of this odor? I don't want to put any sticks in there and make them smell this way.

Thanks in advance.