The ICE does start with the HV battery but you need enough juice in the 12V battery to energize the relay which isolates the HV battery when the ignition is off. I left a laptop running in mine and drained the 12V battery a while back and it completely kills the vehicle. You have to jump the 12V battery to start after that. I have a portable jump starter and just plugging that into the cig lighter plug was enough to energize the relay and start it right up after that.

My 4WD
Wife's 4WD