PowerEdge R715 server won't POST - no lights on the hard drives except for a quick flash when i turn on the power

The server powers on and i see the hard drives light up for a brief second....but no POST, no video no nothing....

I've re-seated all of the drives, the memory, and the cables attaching the drives to the motherboard and backplane (waiting the 2 minutes to power on after I've put the power cables back in)

I've re-seated the power supplies

I've tried in order the steps here including removing the drives and the optical drive before powering on and still no luck:

 

• Remove all external devices except the monitor (including mouse and keyboard).
  • After removing the devices, attempt to POST the server.
    • If the server now completes POST, plug the external devices back in one at a time until the defective device is found. Replace the defective device once it has been isolated.
    • If the server still does not complete POST, go to the next step.
       
• Remove all third-party components and parts.
  • After removing the parts, attempt to POST the server.
    • If the server now completes POST, plug the parts back in one at a time until the defective part is found. Replace the defective part once it has been isolated.
    • If the server still does not complete POST, go to the next step.
       
• Disconnect the hard drives from the server.
  • After removing the parts, attempt to POST the server.
    • If the server now completes POST, plug the parts back in one at a time until the defective part is found. Replace the defective part once it has been isolated.
    • If the server still does not complete POST, go to the next step.
       
• Disconnect the optical drive and any internal tape drive.
  • After removing the parts, attempt to POST the server.
    • If the server now completes POST, plug the parts back in one at a time until the defective part is found. Replace the defective part once it has been isolated.
    • If the server still does not complete POST, go to the next step

 

any suggestions to resolve are appreciated - thank you