Dell Laptop Wont Turn On

I have an old Dell Inspiron 7000 that just stopped turning on a while back. When I plug the adapter into the wall (not connected to the computer) the green light comes on and everything seems fine. However, as soon as I plug it into the computer the green light goes out and begins to blink every few seconds. Of course the computer wont charge or turn on or anything. I called Dell and they just said it was a motherboard problem which seems to be too programed of an answer. I was kinda hoping that its just the adapter and I can just go get another one. Anyone have any thoughts on this? Thanks for any help on this one.

motherboard problem which seems to be too programed <--(^^;?(I cannot understand its correct meaning, but I don't thing it's due to just an adapter too.)

Adapter itself is rather simple structure, so that you can try to apply it to any devices which use the same voltage before you buy again. Or your friends who have a tester should examine it easily.