I have a Hayward pool heater (model #H250FDN). Over the past week, the heater fired up and heated just fine. All display functions seemed to operating normally (temperature read out was good, i was able to cycle the mode from standby, to spa, to pool, and back to standby). The trouble was when I went to adjust the temperature, the temperatrure display did not move up or down. This weekend, when I finally had time to work on it, I see there is no power to the display at all: no service light, no heater light, no light or display of any kind. I checked the breaker and it is fine. The switch to the heater is on. I had a spare display board and swapped it with the same result.
Any thoughts on what I can do to further troubleshoot?