Dell Inspiron 6400 Power Problems

I have an Inspiron 6400 laptop I don't use it much since I use my desktop most of the time to work, last night I was using it and it was running fine, nothing wrong with it, when I was done I turned it off and went to bed,  in the morning I started having power problems, when i press power button the power led lights for a few seconds then fades, and the laptop never starts.

I checked the battery and the charger on anther Dell computer I have and it worked fine, I even removed the hard drive and install a new one and still I got the same problem the power led lights for few seconds then fades, I even replaced the memory with new one yet the same problem.

plz help.