One can go to a local Apple store and buy a replacement there.
Alternatively, one can order a battery from eBay or Amazon and make
the replacement by himself.
As your older brother, I've been where you are—maybe not exactly, but close enough.
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Lao
The path is yours to walk; I am only here to hold up a mirror.
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More answers
The iPod has a built in rechargeable battery so one needs to
make sure the correct battery is used as a replacement. Among the
battery replacement options are Apple itself and repair shops.