Nature's Miracle would have been my 1st thought however my experience is that it DOESN'T work. We had a cat pee on the carpet in our living room and nature's miracle just made it wet.
Try pouring vinegar down there or/and alcohol (I'm into cleanliness). I am assuming nothing will short out though (check me on that!). Vinegar will neutralize the pee smell and alcohol will kill the bacteria so you and/or your family don't have to breath in that sh@#.. before it dies, just in case. Just don't light a match for about 45 minutes.