My MacBook Pro won't turn on

I have an old MacBook Pro (from 2007), and I haven't used it in a few months. It was serviced about 6 months ago, as my mother was going to use it, but she never did. Recently, I tried to turn it on, but it does not respond at all. The light on the charger stays green, even though the battery must need to be charged a bit. I used more than one charger on it with the same result. I tried holding down the power button and resetting the SMC, no luck. I know the battery needs replacing, but it has been this way for a while now with no problems. I have tried removing the battery to turn it on jsut with the charger, and it still gives no response. I am not sure what else to try!