MasterTemp 400 not turning on

[Fadimamar]

I am having a problem with my heater but it is unpredictable, one day it happens and other day it does not. On the remote or on the Easytouch control panel it shows that the heater is on, but in reality it looks like having no power. Then it just works on it is own. Some times it maybe working in pool Mode and if I switch to spa, it goes dead; no lights on display as it has no power at all. On the easy touch control panel Display it shows that spa is on and heater is on, but nothing shows on the display on the heater. It is unpredictable when it works or does not and has no rule or association with spa or pool mode.
I did not measure voltages since the problem is on and off and might be related to other issues. Any idea?
By the way, when it is not working easy touch control panel shows heater on, but On the screen logic App on my phone, the button “Heater” keeps flashing in solid green and light green colors

 

[JoyfulNoise]

Have you opened up the side panels and top? If not, take a look inside the unit and inspect all the power and control wiring. Mice and other critters have been known to make their nests inside the heater, chew up wiring, and urinate/defecate all over the inside causing corrosion and damage.

First step is to open it up and look inside ...

 

[Fadimamar]

Yeah. All seems to be in good condition. Some people also talk about the panel board being rusted from rain, but that is not the case