I have a outdoor wood boiler through a heat ex changer into my indoor NG boiler out to my radiant floors. My question is my Tekmar 356 has no display and nothing is working. could this be bad 24v xformer input or is it a bad controller? What can I do to test to ensure the controller is bad prior to spending 300 on a new controller? I am a disabled vet on a very fixed income so any advice I can get that might save me a few bucks would be fantastic. Thank you in advance.