Optiplex 3020 Yellow blinking power button

My computer is a  Dell Optiplex 3020. The power button is blinking yellow, 2 blinks, a pause, followed by another blink and it keeps repeating and I could not get the computer turned on. Dell sent out a technician and replace the motherboard. I turned on my computer and the same thing is happening, same pattern of blinking. I disconnected the power cable and somehow got the computer to turn on but now I am afraid of powering off. This happened the first time....I could get it powered up about three times but then it was just the blinking button and no matter what I tried I couldnt get the computer powered up. Now, Dell wants to send out another technician to replace the motherboard again. Anyone have another solution?