@RaymondSnel:
Try a look into the TV’s manual. Perhaps you plugged in your cable into a USB port which provides permanent power or gets activated by the TV setup configuration since it should charge devices after the TV went off.
My Panasonic plasma has one dedicated USB port for such purpose, all others are really dead when the TV is powered off.
To protect your filesystem as much as possible, have a look into this thread discussing an automatic file system check on start/stop of OSMC.