Maybe try disabling the watchdog
Edit: I see this in the log.
Sep 11 14:00:27 sp4rkr4t-PC kernel: watchdog: watchdog0: watchdog did not stop!
Sep 11 14:00:27 sp4rkr4t-PC systemd-shutdown[1]: Using hardware watchdog 'SP5100 TCO timer', version 0, device /dev/watchdog0
Sep 11 14:00:27 sp4rkr4t-PC systemd-shutdown[1]: Watchdog running with a timeout of 10min.
So try this:
/etc/modprobe.d/disable-sp5100-watchdog.conf
add
blacklist sp5100_tco