Chosen Solution
Hi all I have a MacBook Pro, Mid 2012, A1278 (EMC 2554). It wont turn on from the power button. Plugging the power cable in powers it up due to the Auto Power On feature. I’m also unable to turn the device off by pressing and holding the button either. The behavior makes me think the Button is at fault, however, unplugging the battery and removing the power adaptor and unplugging the keyboard then shorting the Power Pads on the motherboard also doesn’t turn the device on, This process apparently bypasses the button. Does anyone have any idea what I could try next? I’m not afraid to go digging with a multi meter and I have a schematic and board view and confident with a soldering iron/hot air station. Board number is 820-3115-B Update (08/17/2021) Yes the HDD is backed up The MagSafe was originally orange, but once the battery was charged it turned green. I have checked all of the following Power Rails and they are present and correct: PP3v42PPBUS_G3HPP5VS5PP5VS3PPVRTC_G3H When I short Pin 5 of the Keyboard connector to ground it still doesn’t turn on which is basically what the switch does.
Ouch! This is starting to look like a dead CPU or GPU issue. Let’s give this a try, Disconnect the battery and with another plugged in on the external ports press and hold the power button for a good 15 sec. Now carefully plug in the MagSafe charger did the fan try to start, did the system startup at all?
