We just changed the 9 volt alkaline battery and all works great again.
Hi Deb. Changing the battery wont fix anything. All that battery does is save the programming to the controller in case the power goes out. It wont actually run the sprinkler system.
Maybe you reset the controller without knowing it. If you unplug the controller and take out the battery this will reset the controller. I'm guessing that you probably reprogrammed the controller and now it's working.
Or you just think it's working because you have a display again because of the fresh battery.