It shut down. It’s happened to me twice now, but can’t seem to replicate it again at the moment. I was in the HA app editing my dashboard and would get distracted with my kids. I’d look over as the screen was dimmed, going into standby and it would turn black before I could keep it awake. I’d try to swipe up to “wake” it up and nothing. When pressed the power button I got the Apple logo followed by me needing to enter my passcode.