Charging or not charging?

I just have had this problem:
LED: off
Lockscreen: “Wird aufgeladen”
Icon top left: “Wird geladen”
Battery settings menu: Wird nicht geladen.

I am in the train atm, so my FP2 is plugged into my trusty powerbank which is the only dependable way of charging AND using my FP2 at the same time (I know, unrealistic to expect from ANY smartphone, amirite guys?).

While sighing and thingking “yet another FP2 exclusive”, taking screenshots and looking up the issue on the forum, the loading LED lit up.
Right now its about 30 degrees outside and i have been browsing reddit in the train for an hour or more, chuckling at memes and cat pics.

The bak top part, where the CPU is, is super hot. Maybe the not charging is not a bug but a security measure to not melt the battery because of the heat?