Here are your parts for an EPS could not find EPS3.
Replacement parts for EDW5505EPS3 models | AppliancePartsPros.com

Here is the wiring diagram.
http://manuals.frigidaire.com/prodinfo_pdf/Kinston/16026639.pdf

Could be the control panel or the control board (Item 12).
The usual way to troubleshoot this is to check the panel (keypad)with a meter and if it checks out OK replace the control board. Unfortunately they do not publish a pin-out for the panel so you cannot do this. Keypads are usually set up so that a number of keys use the same common so if a number of keys (usually 3 or so) are not working I would replace the control panel. Still a bit of a crap shoot.

Try this first:
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.