Yardworks review: Replacement batteries

I bought a new battery two years ago add Its already hooped. I can not find a replacement anywhere. Its 24 volt 16 inches [protected])
Please let me know where I can buy one of these. My mower is only five years old. I've had to replace my the battery twice in this short and period of time. The lawnmower is still brand new so it's a shame if I can't get parts for it. Can't get a hold of Yardworks to resolve my situation.

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