So, this is odd and scary. I've just completed my 6th or 7th print with the Duet, using the same slicer (Cura) and same start/end gcode.
I just wrapped up a 9h print and I was monitoring the printer because it was getting close to done. I watched the print head move to a corner of the print and just stop. It sat there for a few seconds while I fumbled with the bed and pulled it out of the way. It had started melting a hole into the print, but thankfully it doesn't impact it much.
I took a screen shot of the web interface next.
I highlighted a few things.
The Duet was reporting 95.6% completion.
Both heaters had beed turned off.
The total layers was reporting 21. It was actually 154, with a last, 155th layer for ironing, which had been completed. (Cura counts ironing as a layer apparently)
The filament usage was WAY off. Or it was accurate and the expected usage was way off.
About 4 minutes after I took the screen shot, the printer homed X and Y, and raised the Z by 5mm as the end G-Code tells it to.
This happened once before, though I didn't see it happened and was scratching my head about it. I printed a small calibration cube and came back to see it stuck to the hot end, off the print bed by about 5mm with the X and Y homed.
My gut is telling me ironing has something to do with this, but all of my prints have been ironed on the top layer for a week or so now.
Here's my end GCode from Cura, I think it's clear this was hit because the heaters were off. Not sure where it went wrong.
M104 S0 ;extruder heater off
M140 S0 ;heated bed heater off (if you have it)
G91 ;relative positioning
G1 E-1 F300 ;retract the filament a bit before lifting the nozzle, to release some of the pressure
G1 Z+5 E-5 X-20 Y-20 F9000 ;move Z up a bit and retract filament even more
G28 X0 Y0 ;move X/Y to min endstops, so the head is out of the way
M84 ;steppers off
G90 ;absolute positioning