First did you try using the heater relay in the motor relay position.
I did find 48vdc on one of the pink wires on the motor relay. The other pink wire showed no voltage even if i pressed the button.
It depends on where you are measuring to.
This could be normal re: one side gets voltage the other is ground.
If you measure across the relay coil and get 48 volts and the motor does not run then either the relay is toast or there is an open somewhere else in the circuit.
What I did find wrong is the thermistor(whirlpool pn 3976615) is OPEN no continuity. What i then did is jump the thermistor to see if the unit worked,
Are you sure you were using the correct meter scale at 70 degrees F it should be 12,000 ohms approximately so you have to be on the 20 K or higher scale. Also this is a negative temperature coefficient device, in other words resistance decreases as temperature increases so if you jump it, the unit would see a high temperature and probably not heat. Disconnect it and it will think it is cold. Also this should only effect the heater not the motor.
Is it possible to have a bad thermistor and even heat board?
Yes it is possible but I do not think the thermistor should have any effect on the motor running.