Mac Basic Startup Troubleshooting Steps

Mac Startup Triage

• Black Screen / No Backlight?
  • Check the power source, power cable, etc.
    • No power? Recycle the Mac's power switch. (see step 1). Reset power breaker/GFI; replace power cable or brick.
    • Power available? For Intel-based Macs, try resetting the SMC. (see step 4) No luck? Chances are it could be the Mac's power supply, logic board, or the SMC.
  • Flashing Power LED / Audio Warnings?
    • Check RAM. If possible, reseat individual RAM modules.
    • Run Apple Diagnostics. (see step 3)
    • Attempt EFI Recovery
• Black, Gray, or Blue Screen / Backlight On?
  • Power-on Self Test (POST)
    • Startup Chime = POST successful
    • Series of beeps = POST failed, check system RAM
  • Mac displays a screen with a folder that has a flashing question mark?
    • Reason: The firmware cannot locate the booter file (boot.efi)
    • Ref: If your Mac starts up to a question mark - Apple Support
    • Use the Disk Utility in Recovery Mode to repair the startup disk. (see step 6)
• Apple logo displayed on the screen?
  • Success: Firmware located and started the booter and the startup process continues.
  • Failure: The Apple logo is replaced with a Prohibitory sign
    • Reason: The booter cannot load the kernel.
    • Ref: If your Mac starts up to a circle with a line through it - Apple Support
    • Use the Disk Utility in Recovery Mode to repair the startup disk. (see step 6)
    • If Disk Utility found no errors or repaired all errors, reinstall macOS.
• White progress bar displayed under the Apple logo on the screen?
  • Success: Kernel is loading macOS
  • Failure: Kernel Panic or recurring rebooting occurs. Temporarily remove all connected peripherals, except, for desktop Macs, the keyboard and mouse. Then reboot the Mac. If the panics continue, review system logs to determine the cause of the panics. If the panics stop, start up the Mac in Safe Mode (see step 2) and add back, one-at-a-time, the removed peripherals until the panics continue.
  • Ref: If your Mac starts up to an Apple logo or progress bar - Apple Support

Troubleshooting Details

(Note: This User Tip is applicable for all Mac desktops and laptops.)

1. Simply try power-cycling the Mac.
2. Boot up the Mac in Safe Mode.
   1. What: Use safe mode on your Mac - Apple Support
   2. How: At boot-up, hold down the Shift key until the Apple logo appears on the screen, then release the keys.
   3. Why: To repair a corrupt file system and to perform a "quick" system disk repair pass.
3. Run either the Apple Hardware Test (AHT) or Apple Diagnostics to uncover any potential hardware issues with the Mac.
   1. Apple Diagnostics (2013-2020 Intel Macs & 2020+ Silicon Macs)
      1. What: Apple Silicon Mac: Apple Diagnostics for Self Service Repair - Apple Support, Use Apple Diagnostics to test your Mac - Apple Support & Apple Diagnostics reference codes - Apple Support
      2. How: For Intel Macs: Turn on your Mac, then immediately press and hold the D key on your keyboard as your Mac starts up. Release when you see a progress bar or you're asked to choose a language. For Silicon Macs: Turn on your Mac and continue to press and hold the power button as your Mac starts up. Release when you see the startup options window, which includes a gear icon labeled Options. Press Command (⌘)-D on your keyboard.
   2. Apple Hardware Test (pre-2013 Macs)
      1. How to use Apple Hardware Test on your Mac - Apple Support
      2. About the "Apple Hardware Test does not support this machine" message - Apple Support
      3. How to Use Apple Hardware Test to Diagnose Mac Problems - OSXDaily
4. Reset the Mac's System Management Controller (SMC) - Intel Macs Only
   1. What: Reset the SMC on your Mac - Apple Support
   2. How: How you reset the SMC is different between Intel Macs with (2018+) and without (mid-2009-2017) T2 chips. Be sure to use the appropriate section in the link above. On the other hand, Apple does not provide a method to reset either the SMC or NVRAM on the silicon Macs. You simply just restart the Mac to reset them.
   3. Why: Resets fans, keyboard backlight, status indicator, battery indicator, display backlight, power button, close/open the lid, sleep or shut down, battery doesn't charge, MagSafe indicator light incorrect status.
5. Reset the Mac's NVRAM or PRAM.
   1. What: Reset NVRAM on your Mac - Apple Support
   2. How: At boot-up, hold down the Option-Command (⌘)-P-R keys.
   3. Why: Resets sound volume, display resolution, startup-disk selection, time zone, & kernel panic information
6. Use Disk Utility's First Aid option in Recovery Mode to check for errors on the Mac's boot drive.
   1. What:
      1. Use macOS Recovery on a Mac with Apple silicon - Apple Support
      2. If you can't start up from macOS Recovery - Apple Support
   2. How:
      1. For silicon Macs: Press and hold the power button on your Mac until “Loading startup options” appears. Select Options, then Continue. If asked, select a volume to recover, and then, select Next. Select the administrator account, and then, select Next. Enter the password, and then, select Next. You should now be provided with the Recovery app. Select the Disk Utility option.
      2. For Intel Macs: Immediately after pressing the power button, hold down the Command (⌘)-R keys until the Apple logo appears on the screen, then release the keys. When at the initial Recovery Mode screen, select the Disk Utility option. Run Disk Utility > First Aid
   3. Why: To verify the startup disk integrity using the Disk Utility's First Aid option.
7. If step 6 does indicate errors, boot up in Single-User Mode and run fsck to attempt to repair them.
   1. What:
      1. Unable to Start Up My Mac - How Can I Repair My Hard Drive? - Lifewire
   2. How: At the command prompt, type: /sbin/fsck -fy <return>
      1. If fsck makes any repairs, you will get a message that says: Files System was modified. If you do, run fsck again until you get the "The volume <volumename> appears to be OK" message.
      2. Exit messages: Issues found = "File system was modified" OR No issues found = "The volume <name> appears to be OK"
      3. Type reboot <return> at the prompt to exit Single-User Mode.
   3. Why: To attempt to repair the startup drive.
8. (Optional) If either steps 6 or 7 result in errors, I suggest you consider using a third-party disk utility, like DriveDX, to verify the drive's health BEFORE considering replacing that drive.
9. Create a new standard user account.
   1. What:
      1. How to test an issue in another user account on your Mac - OWC
      2. How to tell whether a problem is in your Home folder - The Eclectic Light Company
   2. How: System Preferences > Users & Groups > "+" button
   3. Why: Create a new user account to log into to determine if the current user account is problematic. Note: Obviously this option will only be available if you can boot up your Mac to the macOS Desktop.
10. Run an EtreCheck report and post it here at the Apple Support Communities (ASC) so that we can help diagnose any potential issue(s) that we may uncover with your Mac.  
    1. You can download EtreCheck Pro from here or download it from the Apple App Store.
    2. Run EtreCheck from a normal user account. Optionally, you can run it from a user account with Administrator privileges to gain access to additional details.
    3. Select a problem from the drop-down menu to enable the "Start EtreCheck" button. Optionally, you can add comments on what issue(s) your Mac is experiencing, especially to aide others with similar issues with their Macs.
    4. Click on Start EtreCheck
    5. Allow the program to run to completion.
    6. When done, select Report from the left-side window to display it.
    7. Select the Share Report icon, and then, select Copy Report.
    8. Paste the report to your reply post. (Note: The EtreCheck report does NOT contain any personal information.)
    9. Refs: 
       1. Using EtreCheck - ASC (etresoft)
       2. Using EtreCheck to Troubleshoot Potential Mac Issues - ASC (Tesserax)
11. Boot up the Mac in Recovery Mode to reinstall macOS.
    1. What: How to reinstall macOS - Apple Support & Important changes to Recovery mode - The Eclectic Light Company Note: Please review both articles thoroughly to get a full understanding what re-installation options are available to your Mac. Also note the potential impact to your Apple ID.
    2. How:
       1. For silicon Macs: Press and hold the power button on your Mac until “Loading startup options” appears. Select Options, then Continue. If asked, select a volume to recover, and then, select Next. Select the administrator account, and then, select Next. Enter the password, and then, select Next. You should now be provided with the Recovery app. Select the Reinstall macOS option.
       2. For Intel Macs: Immediately after pressing the power button, hold down the <command><R> keys until the Apple logo appears on the screen, then release the keys. When at the initial Recovery Mode screen, select the Reinstall macOS option.
    3. Why: To re-install macOS.
12. Make a Genius Bar appointment at your local Apple Store or Apple-Authorized Service Provider.
    1. Check your device's coverage - Apple Support
    2. Genius Bar Reservations and Apple Support Options - Apple
    3. To contact Apple Support directly.
    4. Note: You can only make 1-week ahead appointments either via the web link above or with an AppleCare+ phone call. The time frame is longer if you go to the Apple Store in-person to make the appointment.

Notes About Kernel Panics

If your Mac experiences a kernel panic at startup it is important to do at least two things:

1. Jot down the time that the panic occurred. This will come in handy when reviewing system logs.
2. After the Mac restarts from the panic, it should prepare a panic log which will be displayed on your Mac's Desktop within a few minutes. You will then have the option to send this to Apple. Although Apple Engineers will review these, they will not respond to you for troubleshooting the panic. That will be left up to you. As such, I strongly suggest that you copy & paste the panic log information displayed into a text document so that you can have it available later. You can then attempt to review it yourself or you can provide it in a future post here for assistance from others. Alternatively, if you missed copying it, a copy of the panic report should be available in the following directory path on your Mac: /Library/Logs/DiagnosticReports. It should have a .panic extension to make it easy to identify.

Additional References

• Playing Safe: what does Safe mode do? - The Eclectic Light Company
• Check your Mac with hardware diagnostics or AHT - The Eclectic Light Company
• How to Reset Mac NVRAM, SMC, or PRAM - OWC