Reset Wirelesstag's outdoor probe's flash memory

I really like the products from https://wirelesstag.net/. However, the product documentation is sometimes less than complete and their staff less than professional. E.g. there is no information how to reset the outdoor probe when you need to associate it with another tag manager (and you have no access to the previous tag manager). They have information (and images) on how to do that for their wireless sensor tags, but not for the outdoor probe. Customers have already asked for this, but it doesn't seem to be a priority for them to add this bit of information.
So here's the image which pins to short-circuit. How do I know? I found out by try and error.