It seems the the latest beta crashes on HDMI hot plug or when the HDMI swich is adjusted. There is a constant nego going on the I2C lines, and no screen comes up. When I swicth HDMI input on the switch (WievHD 501M) tvOS reboots. Serial DY6QKYAVGXH8.
Can you please file a bug detailing your TV/AV setup, and create and attach a sysdiagnose after you reproduce the issue?
To capture a sysdiagnose, hold down the Play/Pause and - buttons on the Apple TV Remote for six seconds, until you see a dialog confirmation on-screen. From there, follow the instructions to AirDrop the sysdiagnose off the device.