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sounds like a temp sensor problem. The temp sensor is "lying" to the circuit board which is showing the wrong temperature. It is time to change the temp sensor. You will get a watchdog signal ----, when the 2 temperature sensor disagree outside the allowable variance.
If it was me and I came back to the same thing as you I would be on the phone and have the tech on his way out to fix/check the tub. If you replace what you think is wrong and by chance do some thing wrong that causes more problems you could cause problems with your warranty. At lease call the dealer and see what they say to do.