How to troubleshoot a navigation system error on a BMW XM?

I recently bought a used BMW XM and the navigation system keeps showing an error. What can I do to troubleshoot this issue?

First, try resetting the navigation system by pressing the power button for 10 seconds. If that doesn't work, check to see if all the cables and connections are secure. You can also try updating the system software or performing a factory reset.

If the above steps don't work, the problem could be with the GPS antenna. You may need to replace it or have a professional look at it. It's also possible that the navigation system itself is faulty and needs to be replaced.