I have the same Macbook that has been ‘dead’ for the last three months. I tried everything, SMC reset, power button held down while plugging the charger in, battery off, battery on.
Nothing worked until today when I tried something different: heat. Lots of it. I ran a hairdryer over the keyboard, top-case and bottom panel (battery cover removed) while occasionally hitting the power button. After heating up the bottom panel, I flipped it back over and tried the power again: success.
Hope this helps someone. I think the trick for this machine now is to never shut it all the way down or to hibernate.