The most important part is to lock the bootloader before booting into the system for the first time, because that will reset get_unlock_ability apparently (at least in my experience).
My suggestion would be:
- Install the system again and don’t boot into Android
- Check if
fastboot flashing get_unlock_abilityreturns1 - If it does, lock the bootloader with
fastboot flashing lock
If you check get_unlock_ability beforehand you should be able to unlock the bootloader again if something fails (patch level mismatch for example).
But, there is still a risk involved, the bootloader is a black box, only Fairphone knows what’s wrong with it and when it bricks your phone, and they haven’t cleared it up yet.