It is true that it may just be loose.
This post shows it has some serious through hole lugs, two each side, which looks like a good start https://forum.fairphone.com/t/fp3-bottom-top-module-breakdown/87022
I think realistically I will not attempt this until I have a spare, and then can afford to trash my existing bottom module. Then, when I open the broken bottom module I will know more!
It is an unusual design in that the outer metal shroud does not extend all the way over the contacts, they are shrouded by the outer plastic housing to some extent. I can’t see anything much like this in the major online distributor catalogs!