Start button beeps, but does not start program

I have a panasonic inverter microwave NN SA651s & it now does not allow the start button to start. all the buttons work, & everything beeps, even the start button but it does not start the program. I went through the online troubleshoot, door closed, unplug, wait 10sec., replug, cancel program/ restart & when pushing the start button it beeps but does not turn on?? Anyone know what this issue is? thanks