I had reason to disconnect the negative terminal of the battery today and did so following the correct procedure. Before I reconnected it I decided to clean the negative battery post useing a brass wire brush. Stupidly I shorted the battery post to the retaining strap. When I started the engine the message "MESSAGE 4 STORED" was displayed. After switching the ignition off the message remained. Also the bcem wouldn't go to sleep. I decided to disconnect the battery again and when I reconnected it everything was OK. Any explanations?