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On the advice of an engineer at work, I shut off the tub at the breaker for 24 hours, then started it up and have now let it run for 24 hours without touching the keypad. This time the tub has heated up to 77 degrees and is holding constant. The digital display does not show any code which would indicate to me that the mode has been changed. Basically it just shows the temperature with a small flashing dot which I believe indicates that it has not yet met the target temperature (the tub is set somewhere between 100 and 104 degrees). To be honest, I did not really buy the explanation that I must have hit some incorrect keypad buttons. During normal use, it is pretty straightforward...arrow up and down for temperaturs and the pump button to turn on the jets.