With regard to the tutorial with the above title, my experience tends to suggest there's another reason for my TT ONEXL rebooting after switch-off.
It depends upon the navcore and map in use (I've several SD cards with different combinations) and the actions in process (how busy the device is) at the time of switch-off.
The more active the device is at the time of switch-off the more likely a reboot.
This all is symptomatic ...