Currently, when it comes to non-Amazon third party sellers of DJI on Amazon, they are all scams! Amazon promotes them as though DJI is the seller. Amazon then sanitizes the scam sellers' terrible reviews with strikeouts pretending that Amazon was...
Short info:
Dji is acting as expected, I enquired again this evening and they are sending me new batteries and a new charging case. I can then dispose of the defective ones...
But I haven't got it in writing yet... more information will follow.
Definitely no moisture, I had unexpected good weather in the northern part of Norway, I fly only in acceptable conditions. The batteries have leaked, what you see there is electrolyte from the battery, i.e. a defect!
Why? I have no idea.