Here are your parts
Parts for Maytag MDBH750AWB Dishwasher - AppliancePartsPros.com

I cannot find a tech sheet for this unit.
Do you have it?
If not check under the unit and on the back of the kick plate to see it it is there.

The sheet should have the pin outs for the control panel (keypad). This lets you check the keys with a meter.
If they check out OK then the normal procedure is to replace the control board.
If one or more keys fail then replace the control panel.
Still a bit of a crap shoot but your odds are better.

If you cannot check the keys then you have to guess which part is bad.
In most units there are often a number of keys that use a common line (connection) so if up to 3 keys do not work but all other keys do work, I would put the keypad at the top of the list.
If more than 3 keys do not work then the control board would be at the top of my list.
If the keys that work/not work change and/or the unit changes it's symptoms then the control board would be at the top of my list.