Sounds like either a control panel (keypad) or a control board problem.

Your model number is missing several digits at the end so I cannot find the correct tech sheet/wiring diagram.

The normal way to trouble shoot this is to check the keypad with a meter.
If it checks out OK then replace the control board.
Still a bit of a crap shoot but your odds are better.

You could try the following but it would be a long shot as it usually repairs open keys/connections and flashing is often due to always closed keys.
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.