What to do with a Mac that won’t boot
To fix your boot up issue, we should first start out by solving any possible software issues, then onto hardware testing and repair. This involves some software and system resets.
1. Manually perform a hard shutdown
A hard shutdown is what you would normally do when your computer freezes up and doesn’t respond to any keys or clicks. If your Mac gets stuck on a blank screen or loading screen, you can manually shut down and restart it to try turning it on again.
A restart could possibly solve some software bugs and help you successfully boot up your Mac. To perform a hard shutdown, just press and hold the power button on your Mac for about 6 seconds until it powers down.
Restarting your computer can possibly boot it up again so you can do more thorough tests on your hardware. Remember though, only do hard shutdowns when you really need to. Always turn off your computer the normal way, that is by clicking the “Shut Down” option from the Apple logo dropdown menu. Hard shutdowns is an abrupt way to turn off your Mac, it can cause software problems or even data loss on unsaved work.
2. NVRAM / PRAM and SMC resets
NVRAM / PRAM reset
The parameter RAM (PRAM) or non-volatile RAM (NVRAM) are both small amounts of memory that stores macOS boot up information. They both are essentially the same thing, just that modern Macs use NVRAM over PRAM. The NVRAM stores less information, just the essentials like the time zone, screen resolution, and your selected startup disk.
When your Mac is taking forever to boot, resetting the NVRAM could be helpful. This resolves startup disk issues back to default settings.
To reset the NVRAM or PRAM, restart your Mac and hold down Command + Option + P + R for 20 seconds. Your Mac may restart. Release the keys and let your Mac start up normally. For older Macs that chime at boot, hold the four keys until you hear a second chime.
The System Management Controller (SMC) is another hardware component that stores key startup settings. It also stores information related to fan and temperature control, keyboard and status lights, and so much more. You could experience problems with power, battery, or slow performance if the SMC is malfunctioning.
Giving it a reset to defaults could resolve your system problems. Depending on your Mac’s model, there are a few ways to reset the SMC:
- Desktop Macs: Disconnect power cord and wait about 15 seconds before plugging it back in. Wait 5 seconds before turning the Mac on.
- Macbook laptops with T2 chip: Shut down your Mac, then hold the power button for 10 seconds. Wait a few seconds before turning on your Mac. Another way is by shutting down your Mac and then holding down Control + Option + Shift (may turn on the Mac). Hold the three keys for 7 seconds, then press and hold the power button as well. If your Mac is on, it will turn off after holding down the keys for another 7 seconds. Release the keys and wait before turning on the Mac.
- Macbook laptops with no T2 chip: Shut down and unplug your Mac. Then hold down Control + Shift + Option on the left, and the power button on the right. Do this for 10 seconds, then plug in the power adaptor and turn on the Mac.
While these two methods can solve some small issues, there’s no guarantee that it can fix your problem. This is especially so when you have a serious hardware issue. Still, it’s worth a try before moving on to testing your hardware.
3. Reset your Mac
Restarting your Mac can only do so much. For more ways to resolve possible software issues, you can also try reinstalling macOS. Before doing so, do make sure you have a backup of your data either from Time Machine or just a copy of your files on an external drive or iCloud. That way you have your important data safe after resetting your Mac.
How to reinstall macOS
If your Mac is having trouble booting up with the current OS, reinstalling a new one is something you could try. Restart your Mac, and hold down Command + R when it is booting up again. This will get you to macOS Recovery. Select “Reinstall macOS”, and your Mac should download and install the right macOS for you.
4. Test and diagnose your Mac’s hardware
Even if you can successfully boot up your Mac again, it’s still important to run tests to find possible issues on your system. The problem could happen again, or even get worse. So it could be beneficial to fix things before they get worse. You can start with Apple Diagnostics, then run more in-depth tests on specific parts of your Mac’s hardware.
Apple Diagnostics is a built-in diagnostic tool that all Apple Mac users have. It is used as a basic hardware test, where you can test hardware like the hard drive, RAM, and battery. It also comes in handy when you can’t boot up your Mac properly, as you only need to turn on your Mac to run it.
To run Apple Diagnostics, restart your Mac and press the D key. You should reach a language selection screen. After you make your selection, a progress bar that indicates that Apple Diagnostics is checking your Mac will appear. If it finds any issues, Apple Diagnostics will suggest solutions and provide reference codes so you can take them to a Genius for help.
As a basic diagnostic tool, Apple Diagnostics might not be able to run the thorough tests that your Mac needs. You might not want to stop here and continue with more testing. This brings us to testing specific parts of the Mac that might be causing your startup issues. The parts essential for normal macOS startup include the hard drive, logic board, RAM, and video card, so we should go from there.
Testing for hard drive failure
When you turn on your Mac, it uses macOS to boot up. This is stored on your hard drive, the startup disk for your Mac. It will certainly run into trouble during boot if your hard drive is faulty. The startup files and OS could be damaged or corrupted by bad sectors, making them useless.
Hard drives do fail over time, and are actually the most common cause of computer startup issues. For Mac users, hard drive failure could cause errors like the question mark folder or infinite loading bar at boot, and slow down performance.
To find out whether your hard drive is malfunctioning, you can use Disk Utility or hard drive analysis software to test it. You can find Disk Utility in the same spot that we mentioned above, from macOS Recovery (Command + R at boot). There you can run First Aid to test and mark off or repair bad sectors.
For more extensive hard drive testing, use hard drive analysis software like WD Data Lifeguard. With this method, we recommend taking out your hard drive and testing it on a different desktop Mac via a USB to SATA enclosure box. This ensures the drive’s isolation and removes other factors that could affect the tests.
If your Mac does have a hard drive failure, all you need to do is replace the drive entirely. It’s an easy process that doesn’t need many tools to fix. Learn more about fixing an Apple hard drive in our guide “5 steps that will help you repair an Apple hard drive”.
Logic board, RAM, and video card faults
The other parts on your Mac that are required for startup is the logic board, RAM, and video card. Failure in either part could also cause your Mac to not boot up properly. So we still have to do a little testing on these parts.
We know that the OS is stored on the hard drive, but some may not know why these three parts are essential for boot up. Simply put, the logic board is the main communication circuit of the entire Mac. Without it, none of the parts can interact or work with each other, nothing will work. Meanwhile, the RAM is responsible for multitasking and storing system settings, and the video card generates a constant visual feed on the screen.
On most Macbook laptops these days, the RAM and video card are both embedded on the logic board. This makes them a part of the logic board and cannot be taken out separately. Desktop Macs are different, models like the Mac Pro have better accessibility to its hardware.
How to test for logic board failure
There is no direct way to diagnose a logic board, it is simply a circuit board where connective points and parts are put on. However, if Apple Diagnostics does find issues with the SMC, you can conclude a logic board failure. The SMC is a small part of the logic board that the Apple Diagnostics can detect issues on.
Otherwise, the only way to test a logic board is by eliminating other issues that involve the hard drive, RAM, and video card. If you don’t find any problems with the other parts but the problem persists, then you might have a logic board issue. Read more about why logic board issues are so hard to detect and repair in our guide “How to test and repair a logic board”.
Once you’ve run through all these procedures, you should be able to get an idea on how to fix your Mac. Some of these repairs are quite easy to complete, such as hard drive replacements. But for more complicated repairs like logic board replacements, you might want to call in an expert to help you out.
Need more help?
Of course, after you’ve tried rebooting or restarting your Mac, you can just choose to bring it to a professional. If your Mac’s warranty has run out or it is too old for a service at the Genius bar at Apple, you can bring it to a third-party repair service like us. At Safemode Computer Service in Inner West Sydney, we take in all computer issues, for both Apple and Windows devices.
As a highly-rated computer repair service in Sydney, our experienced technicians can help you diagnose in no time, and give you a free quote as well (Ts & Cs apple). We also advise and do computer upgrades for older models that need a little boost. We are located in the Inner West suburb of Enmore. Call us or book an appointment today.