Sorry can't really help there. It is impossible to open the Odyssey without breaking something. Some of my little plastic laches broke off, and around the edge marks from screwdriver are visible. Bookeen either has a special tool, or simply destroy the top cover and replace it with a new one opun closing.
As much as I liked Bookeen, I do not want that experience again. Moved on, and a while ago switched to Kindle. The one thing I really miss is the great folder support. But otherwise I believe the Kindles are made of much better quality (material and assembly wise). Good luck on getting yours replaced.