Troubleshooting Computer Shutdown - System Logs to Check, Please?

Hello all.

I installed Fedora 33 on my laptop, on the day of release, and have been using it since without issues. I’ve installed all the updates since, and last week I starting having a major issue: my computer turns off without warning! As if I unplugged the power supply and took out the battery at exactly the same time… THAT abrupt!

I realize this can be due to many things, so I’d like to ask if there is some system log that can provide clues.

Noteworthy observations:

  • Shutdown occurs even when power supply is plugged in (green LED visible) AND with battery power at 100%

  • Have recently been using my laptop connected to a standalone monitor, meaning that the laptop is closed and positioned vertically on a “space-saving” stand… temperature issue perhaps?

  • Usually happens after hours of use (around 3 to 5 hours) - again suspecting a temperature-related issue

  • I dual-boot this laptop into Windows 10 (for gaming) and I have NOT seen the issue while booted into Windows. This may just be coincidental, as I’m usually only in Windows for several hours… and not even every day.

  • I have installed TLP in Fedora 33 (don’t know if this matters much, or at all, since it was installed soon after installing F33.

Anyway… I may be biased, but am suspecting a temperature issue. If you can point me to any log that can help me troubleshoot and prevent the issue, I would greatly appreciate it.

sudo dnf install lm_sensors
sudo sensors-detect
watch -n 3 -d sensors

to get the last boot
journalctl -b -1

last boot grepping for values
journalctl -b -1 -g "thermal|critical|temp"