The master reset for most systems, both engine and house if they are 12 volt, (or 120 volt for that matter) is removal of power..
For example.. I have a digital TV converter made by LG (Lucky goldstar, I have come to think you are very LUCKY if a GOLDSTAR product works 100%, I've yet to be that lucky) IT locks up solid.. The only option is to completly remove power and then it will work when power is restored..
NOTE: I also have a Kenwood TM-733 that is a block of ice as well, That trick did NOT work with it.