My Sta-Rite SR400LP is about 5 years only. Has always worked until now. When you power up, you get the R13 revision info then it goes to 73 degrees (accurate). I have the command temp set at 100 degrees. Then no blower or anything else. And no LED indication on the Fenwal. You do get the "Service Heater" indicator. Gas is available and it is turned on to the unit. All wiring, tubing, and plumbing appear to be sound. Thoughts?