I am having a problem with a HP Pavilion zv5000. I first had the problem with the DC jack being loose, so I got inside of it and fixed that. But then after that, the screen wouldn't come on, it seemed to be running though. so I attached an external monitor and still no picture. So I looked up what I should do, and was told I needed a new motherboard, so I bought a new one and put it in, but the same problem persists, no picture on the screen. any ideas?