Whatever else make sure that you backup content as link in previously referred to resource:https://support.fairphone.com/hc/en-us/articles/210512123-How-to-back-up-your-Fairphone-2
I appreciate that thought of re-installing device firmware maybe outside your comfort zone, but don’t know whether there is a “Fairphone angel” in your part of the world, whom could help you out:https://forum.fairphone.com/t/the-fairphone-angels-program-local-support-by-community-members/33058