Lenovo J Series Desktop Power Issue

[SilverLeaf]

Unit was brought in because it would not power on after a normal shutdown (no fans, no beeps, nothing except a slow flashing green power LED on front panel). Suspected bad PSU. Installed new Corsair CX430...same thing, as before, not even the PSU fan powers on.

I have tried the following to no avail:
* Checked for leaking/swollen caps on MB
* Stripped board to bare essentials
* Checked power switch for continuity
* Replaced weak CMOS battery

I will try a 3rd PSU here shortly, but I have my doubts. At this point, I suspect possibly a faulty power circuit (trigger) on MB. Am I missing anything here? Second opinions welcome.

 

[Kitten Kong]

Tried powering by using the jumpers only?

Or removing the bard from the case, possible short somewhere, missing standoff etc.