Thank you for writing back to me. That usually means that the heater isn't getting enough water flow. Maybe a dirty filter, mis adjusted water pressure switch or a valve in the wrong position. If that is not the case try to turn the breaker off for a minute to see if that fixes it. If not then you are under warranty for two years with them. Just call the factory at 800 447 9667 and ask for Susan. They will get you going again. Digital heaters sometimes do funny things.
Please let me know what it was as I don't have much trouble with that brand.