I can safety guess that your FP2 is shiny new? Which FP OS version it came with?
I may have a theory, but as it involves some sensitive, non-public Fairphone info (yet), I’ll contact the person who trusted me that info and ask for permission to share it in the public. It has to be with hardware and would explain your situation, if I’m not wrong.
Could you try an older FP Open 5.1 release in the meantime? The last 5.1 manual ZIP is here: https://storage.googleapis.com/fairphone-updates/a88b516b-d990-4219-aef1-c23b3c30c104/fp2-sibon-17.04.0-manual-userdebug.zip (don’t forget to wipe your data first, as it’s not backwards compatible). You should see an equally blue screen once booted, if my theory is true.