I ran across this thread while looking for other things and thought I could add something that could help the original poster or anyone in the same situation. Rather than typing the explanation and how to fix this problem, which I don't think is as serious as you may think... I am going to provide a youtube link for something very similar.
This thread is a little old but seems to not have been fully answered or resolved so I am going to try to add something.
https://www.youtube.com/watch?v=FLH2Ns7Zqo8
Assuming this computer is still in the same condition as before, there is an important 3.3V power supply that must be present on the board for the charger and everything to activate correctly. This power supply is responsible for providing power to something called a one-wire circuit which allows the SMC to communicate with the battery and charger. Before power will be allowed into the computer (assuming you have not done the SMC bypass) some conditions appear to have to be satisfied including communicating with the charger and battery.
This 3.3V power supply (more like 3.5V) is actually on all the time even when the computer is powered off. As in the video above, you should check this power supply, assuming you have access to the board schematics and board layout, and it may be something as simple as a single resistor or fuse that went out that is preventing this power supply from turning on and therefore disallowing ever other power rail in the system from being turned on.