If any error messages from the log is not related to your machine crash, that would probably be a power failure due to the damaged power supply. Any log does not help when power failure. Useless, any log process needs power to write error messages to a disk. That is a limit of the log. I knew someone had experienced this problem.
if you need a automatic notification of journalctl for any desktop environment, just install journalctl-desktop-notification-git from AUR.