Yup. I tried Canon's procedure as well... didn't solve the problem. The power adapter (part# K30310) produces output at different voltages across combinations of the 6-pin connector, but since I don't see in the service manual what pins are supposed to supply which voltage level; I cannot diagnose if the adapter is faulty or not. Or, maybe it was the printhead. I'll never know at this point. Canon responded with (paraphrased), "...the MX860 has been retired... and we're not going to answer any questions about it. Perhaps a community member will respond to your question".
It matters not. Eight days after I posted my own message about not-powering-up, we donated the MX860 for parts and purchased an Epson Workforce Pro WF-4830.
Good luck all. Best wishes for your efforts. We're moving on.
