Hi, I've got a similar thread over on another forum but I thought you guys might have some more in depth insight. Also, I didn't see any MacBook specific category so hopefully Laptops is specific enough. Having all this information is important in my opinion for accurately depicting the problem but for Paragraph 4 is the most crucial information if you would like to skim it. I recently purchased a For Parts/Repair Macbook Pro 15" mid 2010 (820-2850) which was missing a drive, ram, and a few other misc parts. I planned on repairing this device and i'm not apposed to throwing some money at it since i got it for less than half of what working ones sell for. I realize this device is rather old but I'm in it for the the sake of learning more about these devices (as well as soldering and logic board repair as a whole among other things).Anyways, the main problem that I've run across now is that the device won't boot on properly. I have another MacBook pro of the exact same year size and board reference number which is a known working good device. I mention this because I've used this device to check and confirm that the LCD display is functional on my model (and it is). So what I've done so far is examine both motherboards under a microscope to spot differences in conjunction with using a multi-meter to test voltages (All of the "always-present" power lines are giving readings within acceptable margins which i can share if it would help) and the schematic PDF and board-view for this model to confirm that there isn't any visible board damage or missing parts. So far i haven't found anything out of the ordinary. So i then tried to boot the computer with the keyboard unplugged using the power-on pads located near the connector for the keyboard. This yielded no results.This next step is the crucial issue that i can't seem to get my head around. when i plug in the internal keyboard and power it on, no activity, however when i leave power connected to the device and flip up the keyboard connector latch on the board the system fans begin to spin. from what I've seen the physical action of flipping that latch to the unlocked position is kicking on some power channel. the display doesn't turn on and there are no other life signs when i do this, only the fan spin. If i push the keyboard connector back in then the fans stop spinning.After countless hours of fruitless searching I'm getting desperate. I know this was a lot to read but i truly thank you for considering to provide any input. Should anyone need any other readings or info please don't hesitate to ask.