I could not find through Google what pin out worked the on switch for the Macbook. It seemed unreasonable to buy a new top case just to find out the Motherboard was at fault. So finding a method to turn on a Macbook without the power button was needed. I determined this by tearing apart the top case (the owner gave me the go ahead as the computer would have been thrown out otherwise). First of all the framework under the keyboard is glued on. After much frustration I found a hammer and chisel worked best. After prying off the framework I removed all keys and protective layers until left with the circuit sheet for the keyboard and power button. The circuit layers were then peeled apart. Picking at an edge with a fingernail will peel back enough to get a grip. You can then pull with some force as the plastic is fairly tough, take some care working the internal edges as the sheet is full of holes which are potential tear points. With the layers peeled apart I was then able to trace the circuit path quite easily. Once I determined the on button locations I completed the circuit with a very fine wire (I just used one of the speaker wire). The Macbook booted so I knew for certain that it was a bad topcase. Though once the frame was pried off I saw corrosion and when tracing the circuit I found the break I just wanted to see if the crossing the pins would work as with ATX boards. Anyways I am posting this so that hopefully anyone in else performing a search trying to find the power pins will have a guide to look at. By the way the board can be completely removed then connect the LCD, a keyboard, mouse, power and SATA drive then boot. If so inclined you likely could permanently affix a power switch and mount this in a case to use as a desktop. Though I did not test an external screen and the battery would need to be connected or the CPU speed drops (at least it does on older Macbooks). Just connect pin 5 to 29 of the Keyboard Ribbon Connector as shown in the picture. From what I can tell connecting the wrong pins causes no damage. Which makes sense since keyboard presses connect the various pins together. This is only tested on the Late 2009 Polycarbonate Unibody Macbook. I would assume this works on other Unibodies with the same keyboard connector. But do not know. Anyone with other Macbooks or Macbook Pro please chime in if you have to try this and it does or does not work. If not please find the correct pin out if you are in the situation of not knowing if the power button or Motherboard is bad. Given how well the keyboard is sealed if the Macbook works for quite a while after a liquid spill then suddenly dies there is a good chance for corrosion of the keyboard.