We all like to joke about IT support telling us to 'turn it off and on again', but it's not much of a joke when your machine won't turn on at all. In this tutorial we look at the steps you need to take to fix your Mac if it won't start up. Also see: How to fix a Mac

While Macs are well-built and for the most part reliable, they are computers nonetheless and, like all computers, they are susceptible to a number of errors that stop them from booting up correctly, and they aren't always due to user error.

Note that regardless of the versions shown in the screenshots, the fixes in this article apply to most reasonably recent versions of macOS, including Mac OS X El Capitan and macOS Sierra, and we would expect them to work on macOS High Sierra too. The menus and interfaces you'll see may look slightly different but the functions should be essentially the same. Read next: How to fix a Mac with a flashing question mark

We also have a complete guide to fixing some of the most common Mac issues.

1. Check your Mac turns on

First, let's find out if the problem is that your Mac won't start up, or that it won't turn on - those might sound like the same thing, but there's actually a big difference.

Press the Power button on your Mac. If you don't hear a start-up chime, you don't hear any fan or drive noise, and there are no images, video, or visuals of any sort on your display, then your Mac isn't turning on at all. You're not even getting to the point where it refuses to start up.

A Mac that doesn't turn on calls for a different approach to one that doesn't start up. If your computer doesn't turn on then you need to do the following:

Check your power connection: Don't be the cliche, check that the power is on and the Mac is plugged in correctly. Or if it's a laptop be sure that the battery isn't dead - and if it needs charging give it a while to attempt to charge before concluding that it isn't going to work.

Try a different power cable or adaptor: It may be that the fault resides with the power cable. If you have a friend with a Mac power cable that fits your machine try it to see if that solves the problem. If it does it could be a simple fix that involves finding a secondhand power cable on eBay (we'd advise against buying third-party power cables that aren't made by Apple as they are much more likely to be faulty and possibly dangerous).

If you recently had a power cut that could be responsible: your power adaptor could have been damaged in a power surge and you may need a new one.

It's possible that the cable was loose and pulling it out and plugging it in again will solve the problem, but we doubt it will be that easy.

Disconnect all accessories (such as printers and USB hubs): Unplug everything attached to your Mac. It could be that one of your peripherals is causing problems with the start up sequence.

If you recently installed new memory or a new hard drive, make sure they are correctly installed and compatible (if possible re-install the old memory or hard drive).

If none of these steps resolve the problem, then you should attempt to reset the SMC (see step 8).

2. Perform a Power Cycle

If you aren't hearing any signs of life you could preform a power cycle, which involves forcing your Mac to restart after killing the power to it.

On a MacBook you need to hold down the power key for ten seconds. You'll usually hear a squeak as the Mac's power is forcibly cut.

Hopefully after waiting ten seconds when you restart all will be well.

If your Mac is a desktop you will need to unplug it and leave it unpluggged for ten seconds before plugging it back in and attempting to restart.

3. Check your display

If you are using a desktop Mac, it could be a problem with your display, rather than the Mac itself. Have a listen to your Mac to see if it's making any sounds during boot up.

It is possible that your Mac does turn on, but doesn't boot up because it can't access the display - if that's the case you are most likely having trouble with the display hardware (rather than a broader start-up issue).

If you think it's a problem with your monitor, then take a look at this Apple Support document for advice on troubleshooting a non-working display. Apple advises that you:

  • Check the power supply to the Mac (and the power to the display if using a separate unit).
  • Confirm that all cables are connected securely.
  • Check that the monitor is compatible with your Mac.
  • Remove all display extenders, switches and any other devices between the Mac and monitor.
  • Unplug the video cable (if using a separate monitor) and plug it back in.
  • If using more than one monitor in a "daisy chain", unplug all monitors and test using just one.
  • If possible try to use a different display, or a different adaptor (use DVI instead of VGA, for example).

Apple then advises users to try resetting the PRAM or starting up in Safe Mode and adjusting the resolution in System Preferences. (Both of these steps are covered further down in this article).

OS X Recovery Mode

4. Run Disk Utility in Recovery Mode

If your Mac is booting, but the operating system isn't loading up you may have a corrupted drive. Luckily it is possible to fix this in Recovery Mode.

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

Make sure the Mac is off. If it's not responsive because it's stuck on a grey, blue or white screen, just hold down the Mac's power button for several seconds until it gives up and shuts off.

Hold down the Command and R keys, and power the Mac back up again. Keep pressing Command+R while your Mac is booting up.

Once your Mac starts in Recovery Mode you will gain access to Utilities. Click on Disk Utility, locate the icon for your Mac's drive, and click Verify Disk.

If there are errors with your disk Disk Utility should find them and ask if you would like to repair them. Click Repair Disk if this is the case.

In Recovery Mode you can do the following:

  • Restore from a Time Machine backup
  • Use Disk Utility to verify and repair connected drives
  • Check your Internet connection
  • Get help online using Safari
  • Install or re-install macOS (we discuss this below)

5. Boot up your Mac in Safe Boot

Safe Boot limits what checks and functionality your Mac focuses on during startup, and performs certain diagnostics. It's rare, but sometimes you can get your unhappy Mac to start up successfully with a Safe Boot, and then restart it normally, and everything returns to hunky-doriness.

Shut the Mac down, and start it up while holding down Shift. Safe Boot can take a while (if it does work at all). To get some feedback about what's happening, you might choose to start up while holding down Shift, Command and V: that enters both Safe Boot and something called Verbose Mode, which spits out some messages about what Safe Boot is actually trying to do as it goes.

How to fix a Mac that won't start up: macOS Sierra

6. Check the file system

This step is actually kind of fun - at least when it's not your Mac that's under the weather. It's fun because it feels so geeky.

Shut the Mac off, and start it up again while holding Command + S to launch in Single User Mode. You can release the keys when the intimidating black screen with messages in white text appears.

Wait until the command-line prompt appears, when all the text is done scrolling past. Then type fsck -fy and hit Return. And wait. Possibly for several long minutes.

Eventually, after five different checks that take varying amounts of time, you should get to one of two messages: "The volume [your Mac's name] appears to be OK" or "FILE SYSTEM WAS MODIFIED." If you encounter the first message, type reboot and press Return.

If you see the latter message, though, you'll want to run fsck -fy all over again. You can retype the command and hit Return, or press the Up arrow once and then press Return.

If this doesn't work, and your Mac still doesn't start up, then move on to the next step.

7. Reset the PRAM / NVRAM

In the PowerPC days, we talked about resetting the PRAM. On modern Macs, the real term is resetting the NVRAM. The name refers to special memory sections on your Mac that store data that persists even when the Mac is shut off, like volume settings, screen resolution, and similar options.

Resetting that data isn't harmful, but quite frankly it's also rarely genuinely useful. But it can't hurt.

You might need to grow an extra finger or two for this one, or have a friend help you out. Hold down all of these keys: Command, Option (Alt), P and R, and turn on the Mac (it's the same keys to reset the PRAM). Keep holding the keys down until you hear the Mac restart again. Apple says to let it restart just the one time; I usually listen for a second reboot, and then release the keys.

In some cases, after performing this step, your Mac will restart normally. In other cases, you might instead see a progress bar on startup. If the progress bar fills up and then the Mac starts up, you're probably good to go. In some cases we've seen, however, the Mac shuts down at around the halfway point in the progress bar.

8. Reset the SMC

In some situations, you may need to reset your computer's System Management Controller (SMC). This is largely a last-ditch attempt to fix the current version of macOS before attempting to recover the data and moving on to re-installing the OS.

On a Mac laptop press Shift+Control+Option/Alt at the same time as you plug in the power cable.

If you have a Mac desktop, unplug it for 15 seconds and then plug it in and after five seconds press the power button.

How to fix a Mac that won't start up

9. Use Target disk mode

This step should be taken prior to reinstalling macOS and it depends on your backup situation. You do make regular backups, right?

If you're not sweating at the moment, and are confident in your Time Machine or other backup solution then skip to Step 10. But if you wish you'd backed up your Mac then now is the time to see what you can salvage from the machine.

For this, you'll need a second Mac. If you haven't got one then ask a friend. Follow these steps to use Target Disk Mode:

  1. Connect both Macs together using an Apple Thunderbolt cable (it also works with FireWire cables on older Macs).
  2. Switch off your Mac (hold down the power button if necessary).
  3. Start up your Mac while holding down the T button on the keyboard.
  4. Keep holding the T button down as you hear the startup chime and keep it pressed until the Thunderbolt icon appears on your screen.

This places your Mac in Target disk mode. In Target Disk mode your Mac acts like an external drive. You should now, hopefully, see the hard drive for your Mac on your second Mac's Finder.

You can grab the files you need from your hard drive, or even clone the entire hard drive to another external drive.

10. Reinstall Mac OS X or macOS Sierra

Remember OS X / macOS Sierra Recovery from Step 4? You can use it to reinstall Mac OS X or macOS Sierra too. Boot into Recovery mode, and then click to install the latest OS and follow the on-screen prompts.

Our article on resetting a Mac to factory settings has more information on cloning hard drives and reinstalling Mac OS X and macOS Sierra.

11. Make a Genius Bar appointment

If you've made it this far and your Mac still doesn't work, you'll need to take it in to an Apple Genius Bar to see if they can help you fix it (or arrange for a repair under warranty). Hopefully you have got enough data from your Mac so as to be able to back up, or continue working on a new Mac.

Additional reporting by Lou Hattersley