On a DNA40, I believe that letting it sit overnight will do a real reset. It appears to power itself down after a long enough period of inactivity, something that the DNA20 and DNA30 did not do.
On my unit, after an overnight sitting, I hit the fire button briefly and get the splash screen "Evolv dna 40" and the ohms of my nickel coil is displayed as 0.00 ohms. Then if I fire it, it will then display the ohms of the coil. Does anyone else's dna 40 wake up with 0.00 ohms displayed after sitting overnight?