I need help. Heater was working fine a week ago. Heated pool overnight and it was maintaining 76 degrees, I believe it was not heating/ignited at the time and just maintaining the 76 degrees in morning when I raised the temp from 76 to 78 and suddenly the panel went out. After fussing with the circuit breakers and manual temp limiter switch for hours I was able to get the panel to light again. It ignited but then shut down after 5 seconds and gave me error code SF. I purchased a new thermistor and installed and it did not fix the problem. I was told by Hayward to replace the control panel. I did and when I installed, the screen read the correct pool water temp but when I switched from standby to "POOL" the panel blanked out again with no error codes. The control panel screen will now not light up again. Any ideas?