Has the machine ever worked? If so, did anything happen at the specific time that it stopped working?
Are you using a 65-watt AC adapter?
I'd remove the battery, because it's just complicating the issue -- you have a bigger problem, which is a computer that is not starting up.
I'd pop the top and verify the cables connecting the topcase/keyboard are properly seated. If that's not the issue, disconnect the topcase/keyboard, and trigger the power-on pads on the board with metal tweezers to see if it powers up. If it does, the topcase/keyboard is the issue, and if not, the machine has bigger issues, and we can go from there.
Also, re-seat the RAM, and test the RAM slots by powering on with one slot empty, and then with the other slot empty.