Thanks stevo666 for the hint. It actually worked. Disconnected the battery, waited 15 minutes and then reconnected the battery. The result: the Morgan came back to life :-)
The question that comes to my mind is about the cause. This is already the second time that this error pattern has occurred. After about a week of parking in the garage, the Morgan is dead and can be brought back to life by disconnecting the battery. This can not be a permanent condition.
