How did you use it and how frequently did it fail Joe?
Did you have a logger running on a PC and use it to activate the DVK using the appropriate macro commands? If this is true, I would test repeatedly with no or low RF output into a dummy load.
Or, did you use the K3 M1 button? If this is true, I would remove and re-seat the DVK board.
I have never had my DVK fail on either K3 regardless of the method I use to start it. I use it almost daily.
73, Bill, K8TE