First of all, I envy your weather in December. My top won't be coming down for at least 4 months!
It sounds like there is an issue with one of the top sensors. It may be faulty, and not reading the open/close position of the top correctly. I would search the forums for the service manual link. You can download a PDF file of the convertible top service manual and browse through that. There is a large troubleshooting section, and it should provide detail on that code. The Nissan dealer should have done that, but I know with the scarcity of roadsters they don't typically handle convertible top repairs, and pass the buck to a separate shop specializing in that.
Good luck!