Can't end phone calls because of black screen

[freibadschwimmer]

Yes, so it it described here as well:

FP2 Screen can't be reactivated during/after calls - See first post for Workarounds

Solution: Please follow the official troubleshooting tool.

archived text

Besides a badly calibrated sensor the next most common reason for this issue is dust between the proximity sensor and the screen. For more info check <a href="https://forum.fairphone.com/t/fp2-screen-cant-be-reactivated-during-after-calls-see-first-post-for-workarounds/11874/148?u=paulakreuzer">this post</a>. Cleaning tips: Clean the screen of your phone, especially the part where the proximity sensor…

But note that this thread here relates to FP1, the bug fix with recalibrating the proximity sensor only works for FP2!