While there may not be an actual 'crash' per usual windows experience, there may be a report.
In Safe mode, you can check and change some items. Third party extensions and software bits
may be the cause of an unexpected shutdown. There is a method on how to use Safe mode.
A good overview of what is going on in a Mac, can be had by getting Etrecheck and run the item
as it will generate a report; this report can be uploaded to your Apple support discussion page.
Etrecheck information:
https://etrecheck.com/faq
https://etrecheck.com/index
This utility was created by a long term Mac user and contributor to these ASC discussions.
Recent developments have caused him to revise this tool, use it sparingly; after 5 free runs,
there is a cost to get the more complete Etrecheck tool. ~ I've had and used this, as well as
another one also by a contributor to ASC; the MalwareBytes for Mac which formerly went by
the name AdwareMedic. This also evolved from freeware with DIY troubleshooting methods.
http://www.adwaremedic.com/index.php
Without any helpful tool, you can look around to become familiar with the inner sanctum but
usually most stuff will not mean much. Those 'cleaner apps' should be steered clear of due to
the fact they can remove parts of the macOS and don't discriminate between good & bad.
You could look in System profile or report page (loads from About This Mac) and choose from
buttons beneath main 'topside menu' sections; & should open separate window & application.
Mine says "System Information" for that window and co-launched utiity/application. Logs and
other stuff can be read from this accumulative source.
Your 'second window' may be called by another name in latest macOS. I'm running 10.11.6 in my
Late 2012 Mac Mini i7 2.3GHz quad-core (server.) This also dual-boots into 10.9.5 original OS X.
First HDD is partitioned for two OS X, the second HDD has 2 partitions and contains no systems.
If you have a complete backup (and perhaps duplicate/clone or copy of older system on externally
enclosed hard drive) you could use those to further troubleshoot. ~ Complex interactions within or
between various software may make a system unstable. Items from different makers; or the use of
unnecessary antivirus, etc can cause issues.
In these different older systems, some items do the same things, while appear by different name.
(El Capitan is stable and does what I need; I have older G4 Mac mini with 10.5.8 for vintage apps.)
There also are more technical methods that require deeper understanding of how macOS works
such as command-line and single-user, terminal utility among other access points under the GUI.
Perhaps someone else may help you; as I've got many offline issues & problems to solve right now.
Sorry to not have a specific set of steps to troubleshoot. Sometimes you have to be prepared and
be able to fully install the system over again; with several backups of different types..
{Try the preceding ideas as there may be some answers in there; no one had add to
this thread when I began a reply. ~ And I've had issues with this site today.}