Somewhere out there, at my old job, there's a cardboard box with a few puffy laptop batteries in it. I have no idea where it went 🙃

This is why i prefer rechargeable AAA cells. Just take them out. But built-in akku? Either store it fully charged and risk a fire. Or discharge it and you need to take the device appart, before you can use it again, because akku dead.

There really should be a flat akku cell standard though.