I had a K machine that needed a Power logic Board due to a false 9V battery alarm. When I replaced the board I got this WD:Fail Long Pulse message after 15 seconds of startup. I checked the board in another machine and it works just fine. I have a feeling this is something very stupid since I'm not the original tech that troubleshot the machine.

Check all your connections. (ie. All ribbon cables to motherboard, connection from power supply to motherboard etc.)

I just finished doing that. Earlier I found the blood pump cable loose but reconnected it with no change in the symptom.

The first time I had this problem i called the big "F". They told me it could be any one of the boards in the card cage and also it could be the power control board in the power supply. The first time it happened it was the power logic baord and the times after that it was always the actuator board.
Hope this helps, keep us posted.

Thanks for the help guys. It was a bad actuator board.