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Help with Robotic Lawnmower!

I have a Gardena robotic mower that I did not install, but do have the instruction manual and app installed on my phone. Basically I need someone with experience with these to check that it is working and give me a proper lesson in using and maintaining it. It has stopped returning to the charging station when parked, and the app is telling me there is a problem with the guide wire. I wouldn't even know where to look for these issues or how to fix them.