Hello everyone. Just Joined. Have a Jandy Lxi heater. Last year upon starting up the heater worked in pool & spa mode but display was blank. Was able to change temp and measure with external thermometer. All was good and saved $550 on new user interface board. This year the display is blank and heater will only work in spa mode. How can I diagnose this to the user interface board? Don't want to spend $$$ if the board is not the problem. Anyone else experience this?