I made an automatic update of my FP2 and after that the screen went black.
I followed the forum, and thus tried rebooting, taking out battery and simcards, but it stays the same. It charges, and when turned on I hear it receiving messages, but the screen stays black. I also tried taking the screen off and putting it back on again.
I performed a manual update which seemed successful, but the screen remains black. Only difference is that when I reboot it vibrates three times and then the LED in top left corner blinks blue. If I take out the battery and start it again, it again seem to be “working” (it charges and sms are received) but the screen stays black.
I once changed the screen (a year ago) and then got it to work after a manual update. With this update, the screen was working fine before and nothing was changed in the hardware.
That’s the indication for the phone being in dic:fastboot mode since OS version 19.02.1, which is the most recent version currently.
Normally, to boot the phone into fastboot mode you would have to keep Volume - pressed while restarting or rebooting the phone. A manual update offers a reboot at the end of the process, but this would reboot the phone into the installed OS, not into fastboot mode.
If the phone boots into fastboot mode on its own, you could try whether it makes a difference if you take the cover off and boot the phone without it (to keep somehow stuck buttons from interfering).
Apart from having a look at the blackscreenguide, which includes things you tried already … do you happen to have fairphoneangels in your vicinity, who could perhaps try swapping the display module to see whether the display module is at fault?