I have a Kitchen Aid Superba Mod kemc307kss05, SERIAL # XT0702305 – it does not heat up. The display works, but after setting it, it just says Lo and stays that way. I cannot hear a fan go on either. I did have a repairman look at it a while ago and he tried to replace the thermal fuse in the front and said that did not work and told me I would have to replace the whole control panel and it was going to cost about $550. I am trying to do a little research to see what else I can try first. It sounds like maybe try the thermal fuse in the back of the oven and a new blower? Any ideas here to help save me $100s would be greatly appreciated? Thank you. 
Here are your parts
Replacement parts for WHIRLPOOL KEMC307KSS05 30" BUILT-IN ELECTRIC DOUBLE OVEN THERMAL CONVECTION LOWER CRISPWAVE MICROWAVE | AppliancePartsPros.com
See the attachment for the tech sheet
Here is a manual which may help
Whirlpool KAC-25 KitchenAid Built-In Microwave Oven Combination Service Manual - ApplianceDigest.com
You may have to join the site to download the manual but it is free and this is a very good site for manuals.
I would check for 240 volts first.
Next would be the oven’s thermal cut-off, see pages 3-20 and 3-40 in the manual.
Be sure to kill power to the unit when working on it.
Tech Sheet - 8303852 - KEMC378KSS04.pdf (418.2 KB)