The battery might have the voltage, but it takes amperage to operate the starter. Did the store load test the battery? If the bike is rideable, try push or "bump" starting it. In gear, key on, clutch in, bike in gear. Start it rolling and then pop the clutch out so that the rear wheel spins the engine - just as the starter would. Once it fires up, you can let it warm up for a bit then shut it off and try the starter. If it is still a fail, then it looks like a battery is in your future. Tender or not, some batteries just die with age.
Could also try jump starting it using a friend's bike battery and cables, if you have them.
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