I took my mac book to Argentina apple store and I think they have changed my battery, how can I know it for sure?

Where can I find the battery serial number? is it that possible? so I can compare it with the ones I have in the original box.

After a week they gave me the macbook, the battery started to expand and now I can't even put it again in the computer! They told me that it was not their problem but I want to be sure that they didn't change it and gave me a damaged one.

Thanks!

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