I checked the main/starter relay and cleaned the connections and greased them with vaseline. I charged the battery full and disconnected the 12 v socket. After that the bike started without any problem. I thought the problem were solved and have used it 3 og 4 times since then. It started perfectly every time.

But today, almost a month after, the exact same thing happened. Just a "click" and the dashboard went black again. I tried once more, after the light came back on, but the same result. After that the dashboard were just black and didn't come back on.

More suggestion on how to fix it?