Kenmore Ultra Wash lights stuck on - no reset available

Kenmore Ultra Wash dishwasher Model 665.16719 has a "Cancel/Drain" light stuck on and will not reset, and unit won’t run. Light was first solid then flashing. Disconnecting power for several minutes and trying reset procedure (Hi Temp Wash - Air dry - Hi Temp Wash - Air Dry) changes nothing. Looking at control board I don’t see anything obvious (no burned components, connector issues, etc.). How can I diagnose further to identify the culprit? If applicable, how can I separate out the control panel circuit board from the push button assembly (ribbon & connector) in the control panel? Also, label on the circuit board assembly reads "Whirlpool Corp. p/n 3384563 and UPC # 8456300057755. Appreciate any insight you can provide. Thanks.