Hi, my name is Mike and I have been in the home improvement and repair field for 20 years. I will be very glad to help you today. Do you have a multi-meter? Can you check that the element is getting voltage and also check the continuity on it?
You also have a high-limit thermostat in-between your heater and control board, You'll need to ohm that thermostat with an ohm meter to test for continuity, should read 0-1 ohm.If you don't have a ohm meter, you can bypass it by taking the 2 wires off of it and connecting the wires together with electrical tape, don't cut the terminals off the wires.The high-limit thermostat is underneath your tub, just take the front lower access panel off and get a flashlight or drop-light and you will see it.
I have replaced what I thought was the thermostat which as you say is located at the bottom of the machine inside a type of sump. Is there another thermostat that I am missing ?
Are you not able to test with an OHM meter? Do you know the part number of what you changed? It is best to test parts before changing them.
Were you able to test the element also?