We have an Optiplex 7010 SFF which will not power up.  The power light flashes - very quickly or dimly - every seven seconds or so.

When I push the power supply diagnostic button (the black button next to the power in jack), the adjacent LED lights green and the fans start spinning.  When I release the button, everything stops.  (No LED, no fans - just the power button flashing dimly every 7 seconds.)  Pressing the power button does nothing - it doesn't light up and nothing spins.  Holding the power button down does nothing as well.

I have tried all of the following:

• Pull and reseat all four memory DIMMs
• Pull two, then three, DIMMs, with the one remaining in slot 1
• Try a different DIMM in slot 1
• Unplug each fan and the speaker from the motherboard
• Pull the four pin connector from the motherboard
• Pull the video card and its fan connector
• Pull the network card
• Try a different power cord
• Remove the CMOS battery, check with VOM (3 volts), replace

After each, I plugged the computer back in and pressed the black diagnostic button, which still lights the adjacent LED green.  The power button continues to flash every seven seconds but pressing it does nothing.

Based on what I have seen in other posts, I am guessing it is the power supply.  Flashing amber is supposed to be a bad PS (I think), but...I'm not sure the light is amber.  (My wife and I disagree on the color - seriously! 8*) - but she thinks it is amber.)

I've tried to be thorough.  Any advice would be greatly appreciated!