Need help trouble shooting my GE Spacemaker Microwave?

I have a GE Spacemaker JVM3670SF02. Model#ZG900016B made in 2004. The unit is has power, and acts like it is working appropriately but for some reason it is not cooking/heating the food at all. I thought maybe I hit a wrong button or something and put it into a mode I am unfamiliar with but maybe its just broke? Can anyone help me troubleshoot? Thanks!