Xbox Turns off after 5 to 10 Seconds

Hey there. My xbox turns off after briefly showing a message on my tv. “Do not turn off console” then turns off. I unplugged the hard drive and was able to get it to stay on and sit, waiting to get signal from the hdd, but I would not get a screen at all and it would still shut down after a couple minutes. but as soon as the hdd is plugged in it will shut off in seconds. I have checked voltages on different components. I heated the board with a blow dryer with no luck. I have soldering ability if need be. Thanks for your help.