Factory battery was probably charged to a normal level and would’ve paired fine when opened if it’d been powered off. It was left powered on from the factory, which is not how it should’ve arrived. My experience is a valid criticism of a just-released rechargeable device and a QA issue. Where do you get off acting like I don’t know how consumer electronics work because I’m criticizing bad QA?
Before you go through a bunch of calibration, I’d see if it happens with a different filament. Those black particles there are likely something with a higher melting point than the surrounding PLA, otherwise they’d “smear” during printing. I’m betting you’re hitting some intermittent clogs. See if the problem happens with a single color filament.