The cancel light is flashing and dishwasher is "on hold" till problem fixed. Booklet says it could be the door not closing properly, but I think it's something else. Is this a job for a professional or can domeone here guide me? Dishwasher has been 'noisy' for some time, since I know it's on its last stages.

Try rebooting it first. See: https://www.youtube.com/watch?v=XJnzzXJcOV4 Then go here: https://www.youtube.com/watch?v=PDPfaAca4PQ

Here are some manuals: https://dl.dropboxusercontent.com/u/8010163/Kitchenaide%20Dishwashers.zip
https://dl.dropboxusercontent.com/u/8010163/Electrical%20Theory%20and%20Diagnosis%20of%20Major %20Appliances%20Service%20Manual.pdf
https://dl.dropboxusercontent.com/u/8010163/Electronics%20and%20Electrical%20Troubleshooting%2 0and%20Repair%20Handbook.pdf
https://dl.dropboxusercontent.com/u/8010163/Whirlpool_Dishwasher_Service_manual.pdf
Look at all of the manuals and get a meter. You may have a bad or mis-adjusted door switch, too. Another thing that goes out is the control board: The cheap Taiwanese capacitors fail. You can see if they have failed-they look like little cans soldered on the board-because they swell up or burn the board.
Here is a video: https://www.youtube.com/watch?v=auJQCRZmYAU
Also: https://www.youtube.com/watch?v=uIDIEACsjDg