Meanwhile I have tried hardcore shutdown by switching the display out and turning it on again afterwards. MagicInfo starts, everything's fine. Schedule is up and running, too. But when I tried to shutdown by remote again, the displays performs something that appears to be a logout of administrator account. Because while logging on by remote again, everything starts up like logging an account in... except MagicInfo software isn't started and the error message "divice is no samsung display" pops up again.
Version of client programm is "V1.0 Build NA-MIIPP-1006.4", if that matters to find out about a solution. Display type is MX460-3.