Same here. Seems like we cannot boot it up via the batteries but I could not find any details on that
On the other hand I powered it on via usb, while the batteries were connected to the screw teminal and when I removed the usb cable the system was functioning. But I only had it like this for 1 minute so I am not sure if this is the way to work with batteries and this model.
I am a bit surprised because this is not mentioned in the documentation