当您的计算机无法启动时，几乎没有什么比您感到恐慌的感觉更糟糕的了。它也经常发生在最糟糕的时候，比如当你面临上课或工作的最后期限时。如果您的Mac无法启动，请不要惊慌。
您可以尝试多种方法来帮助解决问题。在放弃 Mac 之前尝试所有可用的方法——其中一种可能会有所帮助。
Mac 无法启动时的 7 个故障排除技巧(7 Troubleshooting Tips When Your Mac Won’t Start)
如果您无法启动Mac，请尝试以下一个或多个步骤。
1.连接电源(1. Connect the Power)
很多时候，低电量的Mac会拒绝启动。如果是这样，它可能会运行缓慢。
您应该采取的第一步是将电源连接到您的机器。这有两个目的。首先(First)，它确保计算机已插入。虽然这看起来很明显，但很多人都忽略了这一点。其次(Second)，稳定的电源流有时就是启动Mac所需要的一切。如果还是不行，让电池充电几分钟，然后再试一次。
2.交换电源线(2. Swap Power Cables)
如果您的Mac没电，问题可能不在于您的电池，而在于您的电源线。如果您有一根备用电缆，请尝试使用备用电缆。如果您的电缆使用可选的长度延长器，请移除该部分并插入Mac。
目标是缩小电源线可能出现短路或断裂(short or break in the power cord)的潜在区域。您还应该在启动时移除任何外围配件，例如打印机或USB连接。
3. 电源循环(3. Power Cycle)和安全模式
如果您的Mac有电但无法启动（或没有继续超出Apple徽标），请尝试重启您的笔记本电脑。为此，请断开电源线并按住电源按钮至少十秒钟。如果您的Mac是台式机版本，请将其断电至少十秒钟。
此过程会清除RAM中的任何残留内存，并允许您重新启动。十秒钟后，按电源按钮重新启动计算机。重启电源是您可以使用的最简单的故障排除步骤之一。
您也可以在 macOS 中尝试安全模式(Safe Mode)，方法是按下电源按钮，然后按住SHIFT键，直到出现Apple标志并出现登录屏幕。登录(Log)到您的Mac，您应该会在右上角看到安全启动文本。(Safe Boot)
4.使用苹果诊断(4. Use Apple Diagnostics)
如果您的Mac在完成这些初始步骤后仍无法启动，请使用其内置的诊断工具(built-in diagnostic tool)。按下电源(Power)按钮，然后按住D键。按住这些按钮，直到屏幕提示您选择语言。
选择一种语言后，Apple 诊断程序(Apple Diagnostics)将开始运行一系列测试来检查系统中的硬件。这可能需要一些时间才能完成，因此如果没有立即完成，请不要担心。测试完成后，屏幕将显示结果。
根据问题，您的计算机可能会建议修复或让您选择再次尝试测试。还有一些人会提供参考代码，您可以查看这些参考代码以收集有关该问题的更多详细信息。如果测试没有返回任何问题，则意味着您的硬件很可能没有问题。
5. 启动恢复(5. Boot to Recovery)
所有Mac(Macs)都有一个内置的恢复分区，可以访问可以帮助修复各种不同问题的工具。该分区可以独立于机器的其余部分启动，因此即使病毒或其他原因导致您的大部分硬盘无用，恢复模式(Recovery Mode)也可以提供帮助。
按下电源(Power )按钮，然后按住Command和R。等到(Wait)Apple标志出现在屏幕上，然后松开按键。机器将继续启动，直到出现 macOS Utilities菜单。
这使您可以选择从Time Machine备份恢复、重新安装 macOS、在线获取帮助或使用磁盘工具(Disk Utility)。第一步应该是使用磁盘工具(Disk Utility)来扫描您的硬盘驱动器。右键单击驱动器并选择Run First Aid。这将自动扫描潜在问题并修复它发现的任何问题。
如果这不起作用，您还可以尝试Internet 恢复模式(Internet Recovery Mode)，您可以通过在按下电源(Power)按钮 后立即按住Option + Command + R键来访问该模式。
如果一切都失败了，您可以使用此菜单将您的Mac从Time Machine 备份(Time Machine backup)恢复到以前的版本。
6.重置SMC(6. Reset the SMC)
SMC或System Management Controller控制 Mac的许多功能，包括在您打开盖子时唤醒它的能力。重置 SMC(Resetting the SMC)是一个强大的工具，可以纠正许多不同的问题。有几种不同的方法可以做到这一点，具体取决于您拥有 的Mac类型。(Mac)
如果您有台式机Mac，请拔下电源线并等待 15 秒。在此之后，重新插入电缆并再等待五秒钟，然后重新启动您的Mac。这个简单的过程将重置SMC。
如果您有 2018 Macbook Pro，则需要同时按下一系列按键。首先(First)，按住右 Shift(Right Shift)键，然后按住左 Option (Alt)(Left Option (Alt) )键，然后按住左 Control(Left Control)键大约七秒钟。在按下这些键的同时，按住电源按钮相同的时间长度。
完成此操作后，释放密钥并重新启动计算机。
对于其他类型的Macbook(Macbooks)，按住左侧的Shift、Control、Option键以及电源按钮大约十秒钟。释放按键后，重新启动Mac。
7.重新安装macOS(7. Reinstall macOS)
如果没有其他方法，您可以尝试重新安装 macOS(reinstall macOS)。如上所示启动(Boot)进入恢复模式，然后单击(Recovery Mode)重新安装 macOS(Reinstall macOS)。按照屏幕上的提示完成该过程。好消息是，在大多数(most)情况下，以这种方式重新安装 macOS 不会删除您的数据。
但是，如果您的数据已损坏，则无论如何您都可能无法访问它。最好的选择是通过Time Machine执行例行备份，以确保您的信息在任何情况下都受到保护。
如果您的Mac无法正常工作，请不要放弃。自己试试这七个技巧。如果没有任何效果，可能是时候与专家预约了。
Mac Won’t Start Up? 7 Troubleshooting Tips
Few things feel as bad as the sinking sense of panic you get when your сompυter won’t start up. It oftеn happens at the worst possible timeѕ, too, like when you’re facing a deadline for class or work. If your Maс won’t start up, don’t freak out.
There are several things you can try that can help resolve the problem. Try every method available before you give up on your Mac–chances are, one of these will help.
7 Troubleshooting Tips When Your Mac Won’t Start
If you can’t get your Mac to boot, try one or more of these steps.
1. Connect the Power
Many times, a Mac that’s low on power will refuse to boot. If it does, it might run slowly.
The first step you should take is to connect the power to your machine. This serves two purposes. First, it ensures the computer is plugged in. While it may seem obvious, it’s something many people overlook. Second, the steady flow of power is sometimes all it takes to get your Mac to boot. If it still doesn’t, allow the battery to charge for a few minutes and then try starting it once more.
2. Swap Power Cables
If your Mac is devoid of power, the problem might not lie with your battery but with your power cable. Try a spare cable if you have one laying around. If your cable uses the optional length extender, remove that section and plug in the Mac.
The goal is to narrow down the potential areas where there might be a short or break in the power cord. You should also remove any peripheral accessories like printers or USB connections when you boot.
3. Power Cycle & Safe Mode
If your Mac has power but simply won’t start (or doesn’t proceed beyond the Apple logo), try power cycling your laptop. To do this, disconnect the power cable and press and hold the power button for at least ten seconds. If your Mac is a desktop version, disconnect it from power for at least ten seconds.
This process clears any lingering memory in the RAM and allows you to perform a fresh restart. After ten seconds, boot the computer back up by pressing the power button. A power cycle is one of the easiest troubleshooting steps available to you.
You can also try Safe Mode in macOS by pressing the power button and then holding down the SHIFT key until the Apple logo appears and the login screen appears. Log into your Mac and you should see the Safe Boot text at the top right.
4. Use Apple Diagnostics
If your Mac still won’t start after these initial steps, turn to its built-in diagnostic tool. Press the Power button and then press and hold the D key. Hold these buttons down until a screen prompts you to select your language.
After you choose a language, Apple Diagnostics will begin running a series of tests that check the hardware in your system. This can take a bit of time to complete, so don’t worry if it isn’t done right away. Once the tests are complete, the screen will display the results.
Depending on the issue, your computer might suggest a fix or give you the option to try the test again. Still others will provide reference codes that you can look up to glean more details about the problem. If the test returns no issues, then it means your hardware is most likely fine.
5. Boot to Recovery
All Macs have a built-in recovery partition that provides access to tools that can help repair a variety of different problems. This partition can boot independently of the rest of the machine, so even if a virus or something else has rendered the majority of your hard drive useless, Recovery Mode can help.
Press the Power button and then press and hold Command and R. Wait until the Apple logo appears on screen and then release the keys. The machine will continue to boot until a macOS Utilities menu appears.
This gives you the option to restore from a Time Machine backup, reinstall macOS, get help online, or use the Disk Utility. The first step should be to use Disk Utility to scan your hard drive. Right-click the drive and choose Run First Aid. This will automatically scan for potential problems and repair anything it finds.
If this doesn’t work, you can also try Internet Recovery Mode, which you can access by pressing and holding the Option + Command + R keys right after pressing the Power button.
If all else fails, you can use this menu to restore your Mac to a previous version from a Time Machine backup.
6. Reset the SMC
The SMC, or System Management Controller, controls many of your Mac’s functions, including its ability to wake up when you open the lid. Resetting the SMC is a powerful tool that can correct a number of different problems. There are several different ways to do this, depending on the type of Mac you have.
If you have a desktop Mac, unplug the power cord and wait for 15 seconds. After this, plug the cable back in and wait another five seconds, then restart your Mac. This simple process will reset the SMC.
If you have a 2018 Macbook Pro, you will need to press a series of keys at the same time. First, press and hold the Right Shift key, then the Left Option (Alt) key, and then the Left Control key for roughly seven seconds. While these keys are pressed, hold down the power button for the same length of time.
After you do this, release the keys and restart the computer.
For other types of Macbooks, press and hold the left Shift, Control, Option keys, as well as the power button, for roughly ten seconds. After you release the keys, restart your Mac.
7. Reinstall macOS
If nothing else works, you can try to reinstall macOS. Boot into Recovery Mode as shown above and then click Reinstall macOS. Follow the on-screen prompts to complete the process. The good news is that in most cases, reinstalling macOS this way will not erase your data.
However, if your data is corrupt, you may lose access to it regardless. The best option is to perform routine backups through Time Machine to ensure your information is protected no matter the situation.
If your Mac doesn’t work properly, don’t give up. Try these seven tips for yourself. If nothing works, it might be time to set up an appointment with an expert.
