I dropped the phone today, resulting in a flickering screen. Even my fingers were not recognized by the touchscreen any more. I am highly dependent on a phone and started to worry 
Then, as @anon9989719 proposed above, I dismantled the screen, cleaned things a bit (just with a tissue for cleaning my glasses), and put it back together. Now, everything works again. It took me 30 Minutes in total, including reading the instructions to dismantle on ifixit.com
I loved this experience, made me super happy. This repairability of the Fairphone is very innovative. Many heads up to the Fairphone team!! 