Here is your parts breakdown
Model KUDM25SHBL1

Does sound like a keypad problem. The input / output lines are used for a number of different keys in a matrix since all your other keys are OK odds are high that just the Energy Saver Dry key is shot but the whole keypad must be replaced.

Here is your tech sheet
https://www.servicematters.com/d...0Sheet%20-%208051291.pdf

Unfortunately it does not include the keypad schematic
Look behind the units kick plate for the units tech sheet perhaps it will include the keypad wiring diagram.

Anyways here is a diagram from a different unit which will give you an idea of how they are wired (Page 6). Note that yours could be wired totally different.

Using the above example:
You will see that the Start, Cancel and Energy Saver dry all have a common line P1-5. Then each key also shares a line out with other keys.
You need a meter to check the keys.
To check the Energy Saver Dry key the negative lead goes on P1-5 and the positive lead on P1-13. Polarity is important as you have to forward bias the diode. When you press the key the meter should show close to 0 ohms.
Use a 200 Kohm scale.

OOPS!!! Here is the link
https://www.servicematters.com/d...0Sheet%20-%209743814.pdf

Also I missed this
"And the dishwasher will not start when I press start"
Since more than one key does not operate, it is probably a cable/connection problem.

Make sure power is off
I would open up the control panel
Remove the keypad ribbon cable from the control board.
Clean both the receptacle and plug with electronics contact cleaner or isopropyl alcohol. Also can use a toothbrush just be gentle. Do not reconnect till all the solvent has evaporated.

Also check the ribbon cable tracks for a hairline crack. A magnifying glass helps here

Ribbon cable seems to have a connector on the end, if it does not and is the type where just the insulation is removed the end can be cleaned with a pencil eraser. Do not use an ink eraser as it is too abrasive.