We are house sitting for

Question

We are house sitting for friends. They have a Miele Classic, wall mounted combi oven. It has a single dial at the top left of the silver facia. To activate the microwave, I turned the dial one click clock-wise. I then pressed the "-" and " " buttons to alter the wattage. As I pressed the "-" button, I seem to recall the display showing numbers going from 600 to 350 to 150. I then pressed the " " button to increase the wattage. However the display then showed "FOI" and I have been unable to change this. The oven is now not functioning in any mode.Could you please explain how to resolve the FOI display?Many thanksJames [e-mail]