No solution, just encouragement. I've done this on various cars and it's always easy once you find the video that shows you the trick for opening the fob. Keep looking and be specific in the search. If you just get a screwdriver and start forcing the separation you'll likely damage the fob and it won't clip back together. By the way, I just did my 2012 CX-9 and the battery cost $6 at Walgreens. Surprisingly, the local Mazda said they would do it for only $9 so that might be worth a call before you give up in frustration.
I currently have 4 Mazda's that all have remotes. The battery on them do run out but at my dealership in Cary, NC they are more the willing to replace the battery in the remotes for FREE!
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