Laptop won't power up

Hello,

I plugged in the adapter for my Inspirion 4150 and noticed that the green light lit but quickly faded to black. Assuming that the adapter was faulty, I ordered a new one from Dell, only to find the same problem occurs. The laptop itself won't even turn on and I was assuming that the battery was dead therefore the ac adapter usage.

I have recently moved and the laptop was not been powered up for about 5 months. It was working perfectly.

I need to have a proper diagnosis performed but am not sure where to start. Any advice would be greatly appreciated.

Thanks!