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My Mac won't turn on anymore.

Emyle_2636 Posted messages 1 Registration date   Status Membre Last intervention   -  
Didi64_549 Posted messages 2758 Registration date   Status Membre Last intervention   -

Hello, my Mac is a desktop, quite old, and I work on GarageBand since I'm a musician. For almost a year now, it hasn't turned on, except for once a month. I've tried changing the power cable from the outlet, unplugging and replugging the power cable, holding the power button down, but nothing works. This is my personal PC, but I also have a desktop PC that isn't a Mac; I tried swapping the power cable, and bingo, it turns on! Until today. What do you think it could be? Do I need to totally change my PC?

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Didi64_549 Posted messages 2758 Registration date   Status Membre Last intervention  
 

Hello,

See this Apple link, and even if you have already followed these steps, please try again:

https://support.apple.com/fr-fr/102623

Please come back to us and with photos of the equipment, pictures of the issues, etc...., thank you in advance as this helps us help you.

I also found these tests with some solutions for older Macs:

The classics: Reset the SMC

Here too, we are in the classics. The SMC (System Management Control) is a chip that manages the power, charging, and various fairly basic systems of the Mac. It sometimes requires a reset if these sensors are poorly calibrated.

The procedure is as follows:

  • On a Mac with a non-removable battery (from 2009 to present)

    1. Turn off your Mac
    2. Press the Shift ⇧ + Control Ctrl + Option Alt ⌥ keys on the left side of your keyboard and the Power button (right side) for about 10 seconds
    3. Release these keys. You should see the light of your Magsafe charger turn orange and then return to green.
    4. Press the Power button on your Mac to turn it back on.

  • On a Mac with a T2 security chip (MacBook Pro or Air since 2018, Mac Mini since 2018, Mac Pro 2019 or iMac Pro)

    1. Turn off your Mac (by holding down the power button)
    2. Press the Control Ctrl + Option Alt ⌥ keys on the left side of your keyboard and the Shift ⇧ + [Power] keys on the right side for about 10 seconds
    3. Release these keys. You should see the light of your Magsafe charger turn orange and then return to green.
    4. Press the power button on your Mac to start it up (keeping your fingers crossed...)

  • On a Mac with a removable battery (from 2009 or earlier)

    1. Turn off your Mac.
    2. Remove the battery.
    3. Press the power button for about 7 seconds.
    4. Reinsert the battery.
    5. Press the power button on your Mac to turn it back on.

The “SMC Bypass” mode: a little-known diagnostic solution

The “SMC Bypass” mode is quite little-known and therefore rarely used by users for repairs. However, it is a very effective diagnostic solution and easy to implement.

It involves asking your MacBook Pro to start up without considering the signals captured and the controls of certain SMC sensors. Among these sensors are the temperature and fan speed sensors, or the screen opening sensors.

By starting in this mode, if your Mac’s screen sensor is faulty, its signal will be ignored.

Here's how to start in SMC Bypass mode:

  • Turn off your Mac and unplug the charger.
  • Press and hold the power button on your Mac.
  • While holding the power button, plug in the Mac charger.
  • After a few seconds, release the Power button. The Magsafe light should subtly switch from orange to green (or from green to orange).
  • Turn on your Mac normally.

You should hear your Mac start up with the fans running at full speed.

If this is the case, your Mac's startup issue or black screen comes from the SMC chip, or sensors connected to it.

We advise you to entrust your Mac to a competent independent repairer. The Apple Genius Bar will likely suggest a costly motherboard replacement, while this can be repaired by us or one of our colleagues capable of fixing motherboards.

Resetting the T2 chip

This method will only work on a Mac equipped with a T2 chip. We are therefore talking about MacBook Pros equipped with a Touchbar. On MacBook Pro and MacBook Air with an Apple M1 (or M2, M3) chip, also known as Apple Silicon, the T2 chip is in some way integrated into the CPU. The procedure remains the same.

This procedure is not simple, so we wrote a dedicated article about the T2 chip. You will need to follow it to the letter and perhaps try again. It doesn't always work right away...
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