Replaced control panel and control board because control panel LEDs were blinking and DW would not function. Control panel LEDs no longer blink and control panel buttons operate as expected. But DW will not start any cycle, including the diagnostic cycle. After I alternately press "Hi Temp Scrub" and "Energy Saver Dry" a couple times, all control panel LEDs illuminate, but nothing more. If I press "Cancel", the "Cancel" LED remains on; a second press of "Cancel" extinguishes the LED. Pressing "Normal" or "Heavy" or "Light" or "Rinse" followed by "Start" illuminates respective LED but does not start cycle. Leaving DW unplugged overnight does not cure problem.

What diagnostic step should I try next?