It doesn't have any screw and that's why the first step is so hard ... you know, 'break or not to break'.
I'm sure I can see one in the second photograph.
When disassembling units with many small parts, do it on a towel. It saves searching the floor for parts that got away.
Call Yamaha's support number. They are VERY good about replacing remotes. There is a form to fill out, send that with your remote and you'll have a new remote in about a week or so. Absolutely great customer service. Let me know if you need a copy of the return form... I have it saved somewhere.