Unfortunately there are no official Fairphone repair shops that you can visit.
The official Fairphone repair center can only be reached by contacting fairphone support.
for advice how to reache support you can read the wiki,
mayby you can contact one of the Fairphone Angels 👼 The Fairphone Angels Program and Map (Local support by community members)
there is chance that they can help you Troubleshooting your phone
I see you alreddy spoke about the problem on My phone suddenly stopped working - just black screen
greetings
Tom