Whirlpool duet dryer wont start

I have an electric whirlpool duet dryer that wont turn on when the power button is pushed. but i noticed the heavy duty light on the dial stays on unless I unplug the machine. we have already replaced the control board and had a technician out that could not fix it. sometimes it works and that is when the light on the dial will move but mostly it stays stuck on heavy duty and its lit up.