Solved (work around)
Further testing has shown that the TV does use the hour specified in the automatic software download configuration to perform tasks even if auto software download is turned off (I set it to different times of the day, replugged the power, and watched to see what happened).
Around 3 minutes before the configured time the TV wakes up some parts of the system, in particular the USB port.
I have a device that is powered by the TV USB port that is also connected by HDMI ... and the device can use CEC to receive and issue instructions.
The device (Raspberry Pi) was configured to set itself as the active device when it starts up and also to instruct the screen to turn on .... so I simply disabled those 2 settings in the external device and showed the family how to switch sources on the TV.