I have a Sundance 750 hot tub that everything works on except the LCD display or the mother board is faulty. Not sure exactly how to test. While the hot tub is in operation I unplug the cable on the motherboard that runs to the control display and plug it back in. The display works for a while then eventually goes off again. I don't think it's dirty connections that is the problem as they seem quite clean on the one side. However I haven't unsealed the control panel side to check the other end of the cable as I don't have sealer to seal again. Everything else works on it jets heater etc.... Just the display is causing an issue. Is there a way to test the control panel vs the motherboard with a volt meter maybe? Or what could be the problem?