First suggestion, regardless of the age of the machine and/or its warranty status, call Miller service first. They are SUPER helpful and will walk you through some basic diagnostics as well as give you ideas for repairing the machine. Second, if the machine is off warranty, open it up and see if you can observe any visible signs of damage. I might try tapping on the relay to see if you can get it to let loose, or perhaps even change it out (they are usually fairly cheap.

 

Then perhaps get into the habit of unplugging your machine while not in use so random lightning strikes or vehicles hitting telephone poles don't send angry pixies down the line at your welder. 😖

 

Hindsight is 20/20... I have an HTP tig welder as well that's been plugged in for the last 13 years straight, including through the storm that just killed my MM252... and it's still fine.

 

Simple to repair but I cannot help as I am not a Vendor.