@asape I expect it's a wiring issue; -273 is a open circuit, +2000 is a dead short (or mis-configured firmware!). If you want to test the Duet, put a 100k ohm resistor on e1temp pins. I have these for testing:
alt text
Or, as you're using the same thermistor for bed and hot end, plug the bed thermistor wire into e1temp.
Ian