Likely it’s related to this:
https://opensprinkler.com/forums/topic/ospi-ui-not-coming-up-after-update/
If you have previously checked out branch 2.1.8, you can switch back to master branch by going to terminal or ssh to your RPi, and go to the firmware folder, do:
git checkout master
then
git pull
and finally
sudo ./build.sh ospi
Then reboot your RPi. That should fix it.