Just moved new house, panasonic "the genius" microwave (inbuilt into kitchen wall!). It is saying "word prompt, demo mode only" and although will respond to key pad, won't cook as in demo mode. Doesn't respond to pressing start button etc to change mode. Any help gratefully accepted.

"DEMO MODE" is a tool intended for in-store demonstration of the microwave oven to the consumer.
While in Demo Mode, if you push "START", the microwave will not fully operate as designed. To Exit Demo Mode, press the "Timer/Clock" button four times. If it does not work, see to your operating manual.

Once a unit is in demo or showroom mode, it will stay and not exit. It doesn't matter if it's unplugged or not. Look in user manual and see if it list how to exit. Good luck!

Jeanine,
Here is a copy of the manual for your microwave. Check page 11 for instructions on taking off demo mode. http://service.us.panasonic.com/OPERMANPDF/NNH735BF.PDF

Push the "Clock" key underneath the "Warm" key on the control panel three times.

Check that the display shows the time, then program the microwave to cook food as desired.

Read more : http://www.ehow.com/how_7262577_cancel-mode-panasonic-microwave-c994s.html

Press the timer/clock button 4 times. That should disable demo mode.

Unplug it if doesnt its work it may be the pc board

try unplugging it for 10 minutes. Otherwise, try looking at the instructions:

service.us.panasonic.com/OPERMANPDF/NNC994S.PDF

DEMO MODE ON/OFF
Demo mode is designed for retail store display. In this mode, the oven can be demonstrated with no power in the oven.

On the "Timer/Clock: button:

4 taps ON The oven is in Demo mode.

4 more taps OFF The oven is not in Demo mode.

Push clock button 3 times. This sets the demo mode and undoes it too.

You should be able to download your Panasonic owner's manual here.

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