There are a few things you can check. First set the washer cycle to Stop and turn off the unit. Next make sure that the stopcock on the inlet valve is fully open. Then close the stopcock/valve and disconnect the inlet hose. Remove the seal and then the filter (use pliers). Clean this inlet filter with running water. Replace the filter and seal and reconnect the hose to your inlet valve. Reopen the valve (check for leaks from threading problems). Make sure the valve is fully open when you try to restart the dishwasher. Check your incoming water pressure at this valve as well - low water pressure will also trigger the inlet error. Make sure the hose is not kinked.
If the washer did any parts of the wash cycle, then try cleaning the outlet side of the system.
Next clean the combination filter, drain pump and non-return valve. For the filter (near the lower spray arm), turn the handle counter-clockwise. Lift the filter out and remove all debris. Rinse under running water and use a nylon bristle brush to get stubborn stuff out. Pull back the yellow clip and open the filter flap. Clean the underside of the filter with running water again.
Remove the water from the cabinet with any container that works. Raise the locking clamp for the non-return valve. Lift up the valve and clean it under running water. Carefully check the drain pump (now visible with the non-return valve out) and remove any debris. Sharp objects may be present. Move the impellers and completely check the pump for foreign objects and remove them. Replace the non-return valve and secure it with the locking clamp. Replace the combination filter so that it lays flat and secure it with the handle. Make sure that the drain hose is not kinked.
If neither of these solve the problem, you need to call for service. The Waterproof safety system has been triggered and water got into the electrical system of the unit.
Many Miele appliance manuals are here: http://www.miele.co.uk/customer/OperatingInstructions.aspx
. The manual for the Miele G641 is here: http://www.miele.co.uk/Resources/OperatingInstructions/G%20641%20and%20G%20841%20Plus.pdf
. See this manual for pictures of the filters and drain pump area.
I hope this helps.