Very sorry for your plight. This is the first i have heard of a seller getting restricted from one defect, as you said one case you won the appeal (so that one shouldn't count).
The communication ebay sent you about the restriction should outline the reason for it. What did it specifically say in that regard?
Feedback results no longer count in a seller's metrics. This was changed in one of the Seller Updates that came out more recently. Ebay now restricts sellers who have too many defects for cases closed without seller resolution, and/or for canceling sales for out-of-stock reasons. Have you by any chance cancelled any transactions in the recent past? Below is the link to ebay policies regarding defects.
Again, sorry about your restriction and wish you success in your next venture.
http://pages.ebay.com/help/policies/seller-non-performance.html
