I lent my Xbox to a friend, and after I got it back from him, I noticed that when I tried to set it back up, the Xbox just turned on by itself shortly after I plugged the power cable in. I tried to hit the power button to turn it off, but it wouldn't turn off. I unplugged the power from the back, plugged it back in, and then the same thing happened. Does anyone know how to diagnose this and/or how to fix it? Thanks.

Does the power button move when you press it? If it doesn't it's probably just something sticky that got in around the power button and is holding it down and cleaning the plastic around the power button should do the trick.

If the button isn't stuck there may be a short.

It is a known issue when some of the outer pcb tracks get corroded and disconnect. To make sure it's not the power button itself that is stuck, you could disconnect the connector from the Power/Eject board on the mobo. If the xbox stays off, it's a problem with the power or eject button.

Thanks for the replies. Do you have a picture of where to disconnect the power/eject button? I won't get a chance to open the console up until this weekend so sorry if the location of it is obvious. And I'll assume that it's an actual connector and I won't have to desolder it to disconnect it?

Inside the xbox, in the front, there is a yellow set of wires (the only yellow set in the front) that run from the front panel (where the power buttons are) to the main board via connector. Just pull that plug out of the main board. They come out quite easily. Just grab all of the wires in your fingers, close to the connector, and pull while wiggling left to right.

After, reconnect your xbox to AC. If it still comes on by itself, you have the corroded trace issue, and will have to do some soldering to fix it.

I finally got around to diagnosing this console and indeed it did have corroded traces that I could clearly see. I broke out the soldering iron and patched up the traces. Now everything's working normally. Thanks again.