I have a GE Profile Spacemaker XL1800, model JVM1870BF06, manufactured October 2006.

Just this morning, it starting making a loud buzzing sound when I turn it on. Food does not heat and a foul/burnt type of smell is coming from it.

It turns on (duh), tray spins, vent works. I tried turning on defrost and the same loud buzzing sound occurs and I did not hear a change in high vs low intensity. I just heard a little click but the noise level stayed the same throughout the minute or so that I ran it. Didn't wanna run it any longer than that.