I recently found my now-recalled Anker battery pack in a box… in my sweltering attic. I’m lucky it didn’t burst into flames and burn my house down. It isn’t visibly swollen, but it claims to have a 100% charge which I don’t think is possible (it’s been up there for at least 4 years).

For further context, in the summer, my attic can get up to around 130°F.