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Replacement parts for Whirlpool GU940SCGZ2 UNDERCOUNTER DISHWASHER | AppliancePartsPros.com

See the attachment for the tech sheet.

Unfortunately there is not a diagnostic, also this unit does not have a pin-out for the key pad so you cannot check it. The problem can be either the control panel (keypad) or the control board. It is a crap shoot as to which is the problem but I would replace the control panel (keypad) first.

Usually a keypad will have a common line for a number of keys so if that line opens you loose several keys.
I would give the following a try before ordering anything.

Connector Cleaning / Checking
Unplug the unit
Open it up
Remove the ribbon cable from the keypad to the control board at the control board.
Clean the edge connector.
If it is the type where there is not a connector just the insulation is removed, it can be cleaned with a pencil eraser. Do not use an ink eraser as it is too abrasive.
Check the tracks in the ribbon cable for hairline cracks. A magnifying glass helps here.
Would not hurt to clean the connector on the board. Use electronics contact cleaner or isopropyl alcohol and a tooth brush. Be gentle and do not reconnect till all the solvent evaporates.
Reconnect everything and give it a try.