When the power button does not power on the system, you can try to run a magnetized/polarized screwdriver to jump the power pins directly on the motherboard.

You should only perform this troubleshooting if:

1. System does not power on using the front power button
2. Both redundant power supplies are operating normally (Green LED, no Amber LED) and have been re-seated
3. There is green activity on the motherboard, showing the motherboard does have power

Step 1 - Power drain system

1. Power off system
2. Unplug all power cables to both redundant power supplies
3. Press and hold the front power button for at least 30 seconds

Step 2 - Access inside of the system and remove the ribbon cable from the motherboard's front panel jumper pins

If you are unsure how to remove the chassis lid to access the internal system hardware components, please visit Removing the Chassis Cover (TWS-1686525).

Step 3 - Run a magnetized/polarized screwdriver to jump the power pins directly on the motherboard

Below is an example of a set of front panel pins. It is usually at the end of the set of pins that has the PWR and its respective Ground pin. 

If system powers on, then the front panel jumper ribbon cable might be defective.

If system does not power on, then there might be an issue with the PDB or Motherboard that may require an RMA.