I'm still tracking this down and hope for more input. I have a much similar problem where I have fan, light, and panel power but NO heat.
From the YOUtube videos I have been gleaning it seems that either the capacitor, diode, or Magnetron.
https://www.youtube.com/watch?v=DlpYQRgDNtg&list=PLOXxLFh6htmseoVJyFBKeMO1syZsqRh2I&index=3
What I NEED to see/read/know is how to dismantle the Mounted LG microwave properly.
Are there any repair manuals anyone has for this?