Well, I don't exactly remember how the 396 behaved in the cradle, although I don't recall this issue. The issue was a power interruption, but that's another thing.
I'm running the unit off the usb cable and when the ignition is off, it starts counting down until it completely shuts off. When the bike is on again, it turn itself on almost instantly. If the navigation was in progress, it will continue to navigate.
If I cancel the counting down after turning off the bike, the 396 will stay on using a battery power.
As for the battery - this unit battery is useless. It can hold the charge maybe for 10 minutes.
I saw this "standby" screen even when off the bike, but really not sure at what point it is activates.