Well, I thought already that my butt was suspiciously warm, but didn't think of anything bad. It turned out that my battery didn't charge because there was a proper short happening under my seat. This may explain why I smelled something weird earlier already.
So yeah, bad contact due to corrosion, nearly having literally a hot-seat and having to push my bike of an intersection because the wires just broke.
Lesson learned, improvements made, moving on!