Solution:

I did the hard reset. See below for how to do that.

Pixelbook Go Shuts Down: Troubleshooting and Prevention Tips

This formatted report combines your findings and explores potential causes for your Pixelbook Go shutting down unexpectedly.

Problem: Pixelbook Go randomly shuts down.

Possible Causes:

Hardware Issues: While less likely, consider hardware issues if the troubleshooting steps below don't resolve the problem. The age of your device (purchased July 2020) might be a factor.
Software Glitches: Temporary software issues can sometimes cause unexpected shutdowns.
Battery Drain: Ensure the charger is firmly plugged into both the outlet and your Pixelbook. Try a different outlet or charger to rule out power supply problems.
Overheating: Make sure your Pixelbook Go has proper ventilation and avoid using it on soft surfaces that can block airflow.
Resource Overload: Running too many applications or processes simultaneously can overload the system.

Troubleshooting Steps:

Hard Reset: Hold the refresh key (circular arrow key) and the power button for 10 seconds. This can clear temporary glitches.
Software Updates: Outdated software can cause boot problems. Check for updates by going to Settings > About Chrome OS > Check for updates.
Powerwash (Reset Chrome OS): If the above fail, consider resetting your Chromebook to factory settings. This erases all your data, so back up important files first. This can be done from the Chrome login screen.
Reduce Resource Strain: Avoid keeping too many tabs open or running highly demanding applications.

Additional Information:

Resources: