Following the instructions from C14 The last few lines of the "dmesg" output (abbreviated) were: all DM devices detached spawned ... mdadm.shutdown as 3650 ... shutdown succeeded Successfully changed to root pivot returned to initrd watchdog: watchdog0: watchdog did not stop Break before pre-shutdown (shell prompt) I then entered CTRL-D That gave me another debug prompt, and a suggestion to save a file to a USB or elsewhere. However, it rebooted before I had time to try that. I'm guessing that the "watchdog did not stop" is related to the "Command failed" messages.