@neauoire this may or may not help you in any way: I have used a nearly identical flashlight before, it also can take an 18650 battery vs. 3 AAA batteries and a plastic connector.
if you do have one around though, could try to pop one in and see if it works.
@neauoire seems like corrosion until proven otherwise on the water 🙃
@neauoire just dealing with a bunch of corroded batteries myself. white vingar to neutralise before disposal/recycling
@zens baking soda too :)
@neauoire suppose it depends pn whether the battery is acid or alkaline! there are both, i forgot
@neauoire there’s a company Z found that specialises in bags and boxes for protecting equipment from corrosion. our apartment is so humid i think i need it. maybe you do too?
@neauoire
to be fair, I've seen plenty of batteries corroding badly here far from the sea (though we are in a damp climate)