What is your setup using exactly (what Raspberry Pi model/SD-card or SSD)?
When you connect a monitor after startup it often is not showing anything. If you try again, connect the monitor before updating. Your issue seems similar to what is described in this report: Restart issues on 8.0.rc1-4 - System seems to hang · Issue #1888 · home-assistant/operating-system · GitHub
Unfortunately, I was unable to reproduce this so far.