Quick answer
First check power and disconnect all external devices, then try force shutdown and restart. If the Mac still won't boot, enter Safe Mode or macOS Recovery and check the disk with Disk Utility. If that doesn't help, it's likely a hardware failure and service is needed.
How to recognize the problem
- Screen stays black even though fan or startup sound is heard
- Apple logo or progress bar appears and gets stuck
- Mac boots to login screen then restarts in a loop
- Question mark or folder with question mark appears on screen
- Beep codes or three repeated tones on startup
Most common causes
Unstable power supply
Empty battery, loose cable or weak charger prevent proper startup. MacBook sometimes doesn't respond if power is insufficient.
External device blocks startup
A faulty USB drive, hub or device can interfere with the boot process.
Corrupted system or startup files
Interrupted update or damaged startup disk prevent macOS from loading.
Disk or logic board failure
If the Mac doesn't see the internal disk or restarts in a loop, hardware failure is possible.
Incompatible extension or software
Drivers and background programs can cause startup blocks, often only visible in Safe Mode.
Step-by-step fix
- 1
Check power and force shutdown the Mac
Connect the Mac to a charger or power adapter and wait a few minutes. Then shut it down by holding the power button for about 10 seconds, then turn it on again. On MacBook, check that the cable and adapter work, preferably try another charger.
- 2
Disconnect all external equipment
Remove USB drives, hubs, card readers, external monitor and similar, except keyboard and mouse if needed. Try turning on the Mac again. If it boots, reconnect devices one by one to find the culprit.
- 3
Try Safe Mode
On Apple silicon Mac, hold the power button until
Optionsappears, then select the disk, holdShiftand clickContinue in Safe Mode. On Intel Mac, holdShiftimmediately at startup until you see the login screen. If the system boots in Safe Mode, the problem is usually software. - 4
Enter macOS Recovery and check the disk
On Apple silicon Mac, hold the power button until the screen with
Optionsappears, selectOptionsand clickContinue, then in macOS Recovery selectDisk Utility. On Intel Mac, holdCommandandRat startup. InDisk Utilityselect the internal disk and clickFirst Aid, then wait for the check to finish. - 5
Reinstall macOS from Recovery
If the disk is healthy and visible but the system won't boot, in macOS Recovery select
Reinstall macOS. This does not erase personal files, but the process takes time and requires a stable internet connection. Before that, if possible, make a backup. - 6
If the Mac still won't boot after reinstall, check if it sees the internal disk
Re-enter
Disk Utilityin Recovery mode and note whether the internal disk appears in the list. If it's missing or marked as faulty, that indicates a hardware problem with the disk and skip further steps. - 7
Reset NVRAM and SMC only if necessary
On Intel Mac, NVRAM reset is done by holding
Option,Command,PandRat startup for about 20 seconds. SMC reset depends on the model and is not applicable to Apple silicon Macs. Do these steps last as they don't fix software blocks.
If nothing helps
If the Mac doesn't even enter macOS Recovery, doesn't see the internal disk or restarts immediately after powering on, it's likely a hardware failure. Before going to service, note the model, year of manufacture and exact startup behavior, as this speeds up diagnostics. If the Mac is under warranty or you have AppleCare, don't open the case or try to remove the disk yourself. If the disk is healthy but your data is important, first seek backup or data extraction, then repair. For business Macs, check in advance if a backup exists and if work can continue on another device during service.
How to prevent it
- Regularly make Time Machine or other backups
- Install macOS updates when you have time and a stable connection
- Don't turn off the Mac during updates or system startup
- Check battery and power status on MacBook
When to call a professional
Contact IT support if the Mac doesn't enter Recovery mode, doesn't see the internal disk or restarts in a loop. It's also better to leave it to a professional if data on the disk is important or if the device is under warranty.
IT infrastructure maintenance · Servers, networks, backup, security and helpdeskFAQ
Will I lose data if I reinstall macOS from Recovery?
Reinstalling macOS via `Reinstall macOS` in Recovery mode generally does not erase personal files. However, before any such step, make a backup if possible, because unexpected disk failure can lead to data loss.
How do I know if the problem is hardware or software?
If the Mac boots in Safe Mode or macOS Recovery, software is likely the cause. If it doesn't see the internal disk, doesn't respond to the power button or restarts immediately, those are signs of hardware failure.
How long does disk check in Disk Utility take?
`First Aid` usually takes from a few minutes to half an hour, depending on disk size and number of issues. Don't interrupt the process until it finishes, as interruption can damage the disk structure.