Fisher and paykell nemo dishwasher Nemo model 820. Continuously beeps when the start or any other button is pushed. Will not start

I had a similar problem with my Fisher and Paykel Nautilus 920 (same product line more or less as yours). Here's what I discovered was wrong, and how I fixed it ...

Hidden inside the plastic panel at the top of the door, where the operating buttons for the dishwasher are) is is a little switch connected to the door latch that has a blue wire and a cream coloured wire attached to it. What was wrong in mine was the cream coloured wired had become brittle and broken off from the switch. If I pressed any button, all I got was 4 rapid beeps (no error code on the display or anything like that, just the 4 beeps).

If you open the dishwasher door and look inside around the top, you'll see about 6 star shaped screws. These hold the control panel on. You'll need a special screwdriver bit to undo these (luckily I had the right one in a cheap mini screwdriver set I got from eBay that's useful for electronics and computers).

Undo those screws and gently prise the control panel off. (Poke something in the door to stop it from closing completely while you are doing all of this). Check the switch in the middle near the door latch to see if the two wires are still properly attached. In my case the cream one had broken off and fallen back inside the door, but I was able to catch it and fish it out with a pair of kitchen tongs. I used sticky tape to tape it (and the blue one) to the door while I was working so neither of them could fall back inside.

I stripped a bit more plastic off the top of the cream wire then soldered it back onto its connector, then reattached it, along with the blue one, to the back of the door latch switch (take note of which colour goes on which part of the switch before you begin).

Probably the trickiest bit was reassembling the control panel back on. There is a little plastic thing that covers the LED display part that always wants to fall out if you try to do this with the door in the upright position, plus you have to ease the panel back on properly so that the push buttons all line up with the outer flexible covering. I found it easier to lay on my back with the door almost fully open to gently tease things back into position. Also, check that the door latch works smoothly (without closing the door - just squeeze it up and down and makes sure the operation 'feels right'). Once everything is in place, redo the little screws and hopefully you are good to go again!

Ive had this dishwasher for 14 years now and had virtually decided that I would have to buy a new one until I discovered what the problem was and how relatively simple it was to fix. Hope this info helps you or someone else! :)