Why is it not turning on?

I have tried to replace the brick, plug it in an a different outlet, and also checked usb prongs but nothings works. It will turn on for 1-3sec then turn off even using a controller to turn it on. I wish not to open it or send it in for repair due to its cheaper to buy a new one than send it in, but I ask if someone can help me the best they can for this is a rare case to find online. Please help?