Im sorry to hear that.
Inside this panel is a battery that is likley dead and needs to be replaced. They last a few years but they fail if not cycled often. Its easy to replace but you need a special battery for this one.
Also, here is a link to the full user manual in case you need that as well.
You can get a replacement battery from electronics stores like Radio Shack etc local to you or you can order a replacement from Gardtec as well: http://www.riscogroup.com/uk/products/category/gardtec
In any case, I will stick with you until this is complete.
Please rate my service kindly.
Also it is the only way I am credited for my time and expertise with you.
Once you rate, I will be notified and will add your question to my priority list so you can reach me anytime until this problem is solved.
Then you can reach me by simply replying to this message anytime.
Thank you and have a great day!