Just to add to what Samer already said: the latest OpenSprinkler firmware 2.1.0 has added a feature to start a test program or any preset program on the controller using the three buttons. You can also perform emergency stop using buttons. Please check the OpenSprinkler user manual, which is now available at:
https://opensprinkler.freshdesk.com/support/solutions/articles/5000403746-opensprinkler-user-manual-firmware-2-1-0-