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Parts for Maytag MDB7809AWB2 Dishwasher - AppliancePartsPros.com

Below is a link to a tech sheet that is also for your unit.
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Download MDB7709.pdf

The usual way to troubleshoot a problem like this is to check the keys with a meter (see the tech sheet).
If you find a bad start key replace the control panel.
If OK then replace the control board, still a bit of a crap shoot but your odds are better.

If a number of keys with a common line/connection are bad (see the etch sheet for the pin outs) then perhaps the following will help.
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. Use electronics contact cleaner or isopropyl alcohol.
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.