What counts as "power failure"? The upper case of my (5,2) Macbook has stopped working so I'm not able to use the power button to turn it on. I'm currently using an external keyboard/mouse. Here's the problem- In order to tun it on, I have to short the power pads on the logic board which I think is pretty risky if not done properly. I wanna avoid the risk of making the mistake and frying the logic board.

under system preferences -> energy saver -> power adapter, I found "restart immediately after a power failure"

So if there is a "power failure', I should theoretically be able to turn the mac on the next time I plug in the magsafe adapter, right?

But what counts as a power failure? Is just taking the battery out while the magsafe adapter is still attached considered a power failure?
This is similar to functions found in the bios of PC's as described here. I don't believe that functions is supposed to be available on portables, but evidently it is for you.

What explicitly counts as a power failure is loss of power to the motherboard. So that means the battery would have to be removed while the MagSafe is not connected. If the MagSafe is connected, it would not count as a power failure. 

The computer starts up again if the power was cut to it (Last State). So if you yank the power at the log in screen, it'll power back on however if you yank the power after shutdown, it'll stay shut down.