+1 on that. A service dept that can't even diagnose a fault code is not one I'd want working on my bike!
Sounds like time for a new dealer! A quick search of the shop manual (linked in a sticky in the general forum on this site) resulted in the answer. Page 8-112, paraphrasing here, but 10 flashes then off for 2.5 sec means malfunction detected in oil level switch, replace switch.