Rig shuts down completely. How do I access last logs to start to diagnose in Linux?

I have a rig that shuts down completely. I even have a USB watchdog that doesn’t do anything so it must freeze up or do something weird that bypasses a low hashrate?
Anyway, The miner that I have running on another monitor does not display any errors, or show any weird hash numbers for any GPUs. It just shuts down. How can I access a crash log to start diagnosing this?
I am a windows guy and am struggling to figure out what the log says right before shut down.