Hello Cornelia, is the irrigation control new and within the warranty period? Then I would have the part replaced under warranty. If you have managed the programming, it is the control unit. After inserting the battery, you have to enter the time (hrs / min / day of the week) and connect it with "Enter", see instructions. When this is done, the programming will start. This should work with a "full" battery (the cheapest is not always the best) I prefer Duracel.

You're trying to change the batteries...