The Mac won't boot and this is the fix

Apple machines are quite reliable, but even Mac and MacBook have problems. When your Apple computer doesn't boot correctly, follow some of the following tips to fix this error from simple things like checking the power connection to performing a power cycle, booting in mode. Recovery Mode and file system testing.

The fixes in this article apply to most recent macOS versions, including macOS High Sierra and macOS Mojave. Menus and interfaces may look slightly different depending on the operating system you are running, but essentially their functions are the same.

How to fix the error does not boot the Mac

1. 1. Check if the Mac is turned on
2. 2. Perform the Power Cycle
3. 3. Check the screen
4. 4. Run Disk Utility in Recovery Mode
5. 5. Boot Mac in Safe Boot mode
6. 6. Check the file system
7. 7. Reset PRAM / NVRAM
8. 8. Reset SMC
9. 9. Use Target Disk Mode
10. 10. Reinstall macOS

1. Check if the Mac is turned on

First, check if your Mac won't boot or not. If you press the power button on the Mac, you do not hear the boot sound, do not hear the fan running and do not see any images or videos on the screen, it means your computer cannot turn on. In this case, you need to do the following.

Check the power connection

Check if the power is turned on and the Mac is plugged in properly. If it is a laptop you need to make sure the device has a battery and if you need to charge it, wait a while for the battery to be charged and started before you can conclude that the device won't turn on.

Try another adapter or power cable

Maybe this error is caused by the power cable, try another power cable to see if the problem is resolved. If a power failure has recently occurred while using the device, your adapter may be damaged by skyrocketing voltage, in which case you need a new adapter. Finally, check the cable, it may be loose, remove it and plug it back in to see if it can turn on.

Disconnect all accessories

Remove all accessories such as printers, USB devices attached to your Mac because one of these peripherals may cause the Mac to fail to boot.

If installing new memory or hard disk, make sure they are installed correctly and compatible (If possible, reinstall old memory or hard drive to see if it solves the problem).

2. Perform the Power Cycle

If you do not hear any sound indicating that the Mac boots, proceed to full power off and restart (Power Cycle).

On MacBook, you need to hold down the power button for 10 seconds. When you turn off the Mac's power, you will hear a beep for this. After waiting 10 seconds, restart. If you use a desktop Mac, remove the power cord and wait 10 seconds then plug and restart.

3. Check the screen

With the Mac desktop, the problem is not only on the camera body, check the screen because the computer may start up but cannot be displayed on the screen.

In this case, Apple has a few tips for you:

1. Check the power supply for the Mac (and the power supply to the monitor if using a separate part).
2. Confirm all cables are securely connected.
3. Check if the screen is compatible with the Mac.
4. Remove all screen extender and adapter devices or other devices that connect the monitor to the Mac.
5. Unplug the video cable (if using a separate screen) and plug it in again.
6. If using multiple monitors, unplug all screens and check with a monitor.
7. If possible, use another monitor or adapter (for example, use DVI instead of VAG)

4. Run Disk Utility in Recovery Mode

If the Mac boots but cannot load the operating system, your drive may be corrupted. Fortunately, you can completely fix this problem by accessing Recovery Mode.

The first step is to run Disk Utility. On a Mac running OS X 10.8 Mountain Lion or above, you can activate Disk Utility by booting into Recovery Mode.

Make sure the Mac is turned off. If the Mac is unresponsive and only shows a gray, blue or white screen, simply hold down the Mac's power button for a few seconds until it is turned off.

Hold down Command + R and reload the Mac. Continue pressing Cmd + R while the Mac is booting until you see the Apple logo.

When the Mac boots up in Recovery Mode, you will have access to Utilities. Click Disk Utility .

After that, locate the Mac drive and select it. Click on First Aid .

Disk Utility will search for errors on your disk and fix them automatically, otherwise it will show you a message asking you to click Repair Disk in this case.

Once in Recovery Mode, follow these steps:

1. Restore from Time Machine backup
2. Use Disk Utility to repair the connected drive
3. Get online help via Safari
4. Install or reinstall macOS

5. Boot Mac in Safe Boot mode

Safe Boot limits the things that are checked, the function of the Mac during the boot process and performs certain diagnostics.

To boot in Safe Boot mode, turn off the Mac and reboot while pressing the Shift key. Wait for a few minutes to boot into this mode. In this mode you will see that the interface is a bit different, for example, the colored blocks will replace the transparent blocks.

When in Safe Boot Mode, you can run certain tests and make changes that can fix your Mac.

6. Check the file system

To check the file system, perform a Mac shutdown and reboot while pressing and holding the Cmd + S key to access Single User Mode . You can release the key when a black screen appears with a white font.

Then wait until the command prompt appears and scroll through the lines of text, enter fsck -fy and press Return . After doing some checks you will get two messages: "The volume [your Mac's name] appears to be OK" or "FILE SYSTEM WAS MODIFIED". For the first message, type reboot and press Return . However, with the second message, you should rerun the fsck -fy command. You can re-enter the command and press Return or press the arrow up once and press Return .

7. Reset PRAM / NVRAM

PRAM / NVRAM are special memory parts on a Mac that store data even when the computer is turned off like volume settings and screen resolution.

To reset this data, press all the following keys: Command , Option (Alt), P , R and turn on the Mac. Keep these keys still until the Mac restarts.

In some cases, after performing this step, the Mac will restart normally. In some other cases, you may see a progress bar on startup. If the progress bar is full and then the Mac starts, the problem is resolved. However, there are times when the Mac turns off when it is half the progress bar.

8. Reset SMC

If the above still can't fix the problem, try resetting the SMC of the Mac. On a Mac laptop, press Shift + Ctrl + Option / Alt at the same time when plugging in the power cable. With the Mac desktop computer, unplug the power cable and wait 15 seconds to plug it back in, then wait another 5 seconds to press the power button.

9. Use Target Disk Mode

This step should be done before reinstalling macOS and need a backup. Follow these steps to use the Target Disk Mode:

Step 1. Connect both Macs together with an Apple Thunderbolt cable (it also works with FireWire cables on older Macs).

Step 2. Turn off the Mac (press and hold the power button if necessary).

Step 3. Start the Mac while holding the T button on the keyboard.

Step 4. Continue holding down the T button until you hear the startup sound and still press this button when you see the Thunderbolt icon appear on your screen.

With this mode, the Mac will act as an external hard drive. You can get the files you need from your hard drive or even copy all the hard drive data to another external drive.

10. Reinstall macOS

To reinstall macOS, boot into Recovery mode, then click to install the latest operating system and follow the prompts on the screen.

I wish you all success!