Released June 2012, Model A1278. Intel processor with Turbo Boost, Up to 512 MB DDR5 Video RAM

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Black screen and fan revs no chime

My macbook pro 2012 turns on but shows no display and all i can do is see how much battery life it has and hear it rev up the fan like a engine, i can only hear the fan revving up would that mean my logic board is stuffed?

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Connect the power adapter to the Mac. On the MacBook / Pro's keyboard, hold down the Shift+Control+Option keys and the Power button at the same time. Release all keys and the power button at the same time – the little light on the MagSafe adapter may change colors briefly to indicate the SMC has reset.

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We need to know exactly what it will do. I would hook it up to an external monitor to try to isolate the problem. What dos it do when you reset the PRAM?

Here's how to reset your PRAM:

Shut down your machine. Yes, all the way down, not sleep or logging out.

Press the power button and then press command-option-p-r. ...

Hold those keys down until your Mac reboots again and you here the startup chime.

Let go of the keys and let your Mac reboot normally.

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Have already tried that and also resetting the PRAM

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External monitor shows nothing and resetting PRAM does nothing at all

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Most Helpful Answer

If it is not chiming, it means it is not passing POST checks. Try booting it with the battery disconnected. It most likely is the logic board signal ppvcore_s0_cpu, so check that out as well if you have a multimeter (you will need to get a board view and schematic for 820-3115).

Most likely is a logic board issue, possibly dead CPU or voltage leading to the CPU? Check the board for liquid damage as well, and clean if it is present (but note the areas effected).

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I think it's water damaged but i've tried cleaning it with apl alcohol and the same thing still accures, It shows no display on anything and even without the ram and hdd in it makes the same reaction no matter what i do

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Press the caps lock key about a minute after pressing the power button, does the caps lock light up? If so, it is more likely an issue related to the LCD circuit, and the fan spin can be caused by a sensor (for example, bad trackpad can cause this). Have you tried outputting the image to a TV/monitor via cable, to make sure it is still booting fine? Can you add a picture of the area where it was liquid damaged? You may need to take it to someone who has an ultrasonic cleaner, in case there is liquid under any ICs

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External monitor shows nothing on screen, ill try the caps lock method but i dont think it will work

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Ok. If the caps lock key does not light up, it means this is not getting into an OS. Due to it not chiming either, it is not passing the initial checks as I though, so it will be a more complex fault on the logic board. You can replace this which will resolve the issue, or take it to someone who can diagnose and repair the logic board (if possible, could even be a dead CPU)

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