You could contact support … https://support.fairphone.com/hc/en-us.
Apart from that, on the Windows 10 side …
As for things I can think of that you could still try yourself with the phone, if you wanted to with a new phone …
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You could carefully try to remove lint or dirt from the USB-C port with a needle or similar.
(I know, you had the phone for a week, but let’s consider other users perhaps with the same problem finding this topic later. And who knows … can’t hurt to have a look.) -
You could disassemble the bottom module and reassemble it, here’s a guide … https://support.fairphone.com/hc/en-us/articles/360032260272-Replace-a-Fairphone-3-module.