Laptop Won't Power Up

I have an HP Pavillion dv7-1245dx, running Windows7. Its refurbished. I was having trouble keeping it charged and thought it was the DC jack so I had it replaced. This didnt help so I bought a new AC adapter, this didnt help neither. I cant run it on the adapter alone because it shuts off randomly. I bought a new battery and the problem remains. Please help.
Windows 7
Ram: 4.00GB
AMD Turion X2 64 bit
2 processors
ATI Radeon HD 3200
Norton Anti Virus
Motherboard: Unknown
Hard Drive:Hitachi HTS543232L9A300 ATA Device

Sorry I do not know what kind of motherboard I have as I am not able to get into my laptop and look.