Hi, just so we are both talking about the same process you are following the instructions for your microwave as per the manual, a copy of which can be found here.
So with the nothing in the microwave and door closed.
You set the left control knob to 7 oclock position for the Pizza setting, which is a fan and bottom heating element.
Then set the right control knob to the desired temp eg 200 degrees.
Press the rapid heat button which is >>SS at which point your not the symbol appear on the display.
Does the microwave beep when you push the rapid heat button, and what happens when you then press the start >>|| button?
Secondly what other icons are shown on the microwave display (other than the time)?