I would never walk away from the mill as it is cutting. I feel I have a very good handle on how everything works and I still screw things up. I worked in a large shop and you could never leave anything alone. We almost lost the waterjet nozzle to a cut out piece that didn’t fall through, and had an end mill come out of the Hass collet and almost took out the whole machine. Another guy walked away and drilled 80 holes into the $60,000 XY table on the Hass.
Let me know when your up and running again if you have questions