After a flight in rather cold conditions (5° C I guess), I wanted to charge one of my three batteries with the standard charging cable.
Different to my to other batteries, the green lights would only go up to two (instead of four lights) lights.
The lights would go on and out rapidely taking the same time as if the lights would go up to four lights.
Is my battery fatally damaged? Any advise?

Fully discharge the battery first and then try again. If this did not work, plug the battery in the drone and then turn everything on and check the battery levels. and let us know.

Please follow the advice in 2# and provide us a screenshot of your battery information from app. Keep us updated, if the problem remains,

Problem solved!
After discharging to one LED left, I connect the battery to the charger. After some time, the third LED came back (i.e. the LED sequence went from 1 to 3 lights) and finally to four.
The app Reports 100% Charge and normal Status. I hope there will be no bad surprises on the next flight.