I bought my Optiplex 9020 mini tower July 2015. It's been used and moved 7 times and on the last move, the power button became unresponsive. When initially plugged in, one Amber blink shows up on the power button, and no more. I've held the button and nothing. However, if I hold the button on the back of the computer on the power supply, while holding it for 30 seconds, the power button works: I can turn on the computer and log in. Everything shows up alive and well.
Dell support sent me a replacement power supply thinking that was the issue. But even after replacing it, the same issue occurs. One Amber blink on the power button when pressed and held. No more. And again, the computer starts when the back power supply button is held for 30 seconds and the front power button is pressed. The power only turns on while the back power supply button is pressed. Is this an error with the power button or the power cable? When on, there are no problems or error messages.