iPod Shuffle 4th Gen Battery Replacement Repair Guide - YouTube
iPod Nano 4 4th Gen Battery Replacement | eBay
Original Replacement Battery 616-0407 / 616-0467 For iPod Nano 4 4G 4th Generation MP3 Nano4 + Free Tools - AliExpress
Replaced the dead battery in an old iPod Nano I bought (really wanted a cheap Product Red one) and not even 2 days later the replacement battery expanded. I would call this
Old school iPod Nano battery replacement – Fix It Workshop
New 3.7V Li-ion Polymer Battery Replacement For IPod Nano 4 4th Gen+ Tool Kit 616-0407
Apple iPod Nano (4th Gen) - Battery 230mAh | FixShop