Thank you for using ManageMyLife.com. I'm sorry to hear about the issues you are experiencing with the microwave, I know how frustrating that can be.
After doing some research on this model and reviewing the service manual, I would suspect the issue you're experiencing with lack of operation and heat would stem back to the PWB Control Board.
The printed wiring board (PWB) is an essential part of a total electronic circuit packaging system. The design requirements of the PWB must accommodate the various components required to achieve product functionality.
If your PWB Board has shorted, it would essentially cause the Board to not send the appropriate signals for the various components to operate.
I have attached a link to our PartsDirect page where you can purchase the part needed to make the repair. Just click the blue link below to be directed to the web page.
PWB Control Board for model R-930AK
Also, if you feel a Sears Home Service Technician would be a better fit for the diagnosis/repair, please
to be directed to the page to set up service on the microwave.
If you have any further questions or inquiries, please don't hesitate to ask. Thank you for using ManageMyLife.com.