It might not be so much the description at this point. Did you cite 'Didn't fit' as the reason for the Return request?
I only ask because that is a remorse reason, and a seller who offers 'No Returns' wouldn't have had to accept it for that reason. (Had you marked 'Not as Described', it'd have been immediately approved.) Note that your seller had the option to approve it, though. Did you reach out to them before filing?
If you don't get satisfaction here, you can go through PayPal (if you used them) or to your credit card to open a claim.
Edit to add: It never hurts to read and understand eBay's MBG. >> eBay Money Back Guarantee policy
