Also possible, it somehow just lost its charge because that's a thing which can and does happen.
I don't know what the cause is and therefore also don't know if it's permanent. I'll give it a couple of days to fix itself and if it doesn't fix itself on its own then I'll mention it to my parents and probably put it on the shopping list such that they know I need it.
Unfortunately, that means that unless it does in fact fix itself, I'll be walking around rather hairy. Which I really, really hate. But oh well. I can't really do much about it right now anyway. It's not an item my parents would classify as high-importance, so they'd get it only when next shopping in a place where they would be able to conveniently get one, which would be a way's away regardless. The earliest I could have a new one would be Monday night, if not Tuesday night.
Ah well. I'll survive, albeit with some loathing of my lack of grooming.