Mac computer won't boot after macOS Catalina/Mojave/High Sierra update
I have a 5 year old MacBook Pro with Retina display that was previously running Sierra. Last night I started the update to Mojave before I went to bed, and woke up to a computer that seems completely dead. The screen is black, it won't turn on, and I get no lights or sound from it whatsoever when I press or press and hold the power button. The computer is charged, and when plugged in the power cord indicator light is green. But it is showing no signs of life whatsoever. Can anyone help?
Solution 1: Run First Aid in recovery mode
If the only way that you can start up is from macOS Recovery mode, the operating system on your startup disk is not usable again. In this situation, Disk Utility built-in macOS recovery mode is a chance to repair the boot issue.
Step 1: Turn on Mac computer by pressing Power button.
Step 2: Press and hold Command+R keys immediately upon hearing the startup chime. Hold the keys until you see the Apple logo or a spinning globe.
Step 3: Select Disk Utility from macOS Utilities in Mac recovery mode.
Step 4: Select the corrupted Macintosh HD from the left panel of Disk Utility.
Step 5: Click "First Aid" button on the top of Disk Utility window.
Step 6: Click "Run" button to start the repair on the Macintosh HD.
If Mac Disk Utility failed to repair the corrupted Macintosh HD, you need to reinstall macOS or restore from a backup.
Solution 2: Data recovery
After iMac/MacBook won't turn on, the important thing is the data stored in Macintosh HD. If the 'iMac/MacBook won't turn on' issue cannot be solved, you have to rescue the data from failed Mac computer.
M3 Mac Data Recovery is a professional Mac data recovery software which can recover deleted files emptied from Trash, recover data from formatted drive, recover data from unreadable drive, recover data from unmounted drive, recover data from corrupted drive, recover data from deleted/lost APFS partition, recover data from encrypted APFS drive, recover data after iMac/MacBook won't start up, etc.
Step 1: Create M3 Mac Data Recovery bootable media
1) Download, install and launch M3 Mac Data Recovery software on another Mac computer.
2) Click M3 Data Recovery on menu bar and select "Create Boot Drive".
3) Insert a blank USB drive into Mac computer and click "Make bootable".
4) The USB drive will be erased and then M3 Mac Data Recovery starts to create a bootable media.
Step 2: Recover data from unbootable Mac computer
1) Insert M3 Mac Data Recovery bootable media into the failed Mac computer and then press the Power button and Option key (⌥) to start the unbootable Mac computer up.
If M3 Mac Data Recovery bootable media fails to start up your unbootable computer, please install macOS on an external hard drive and then boot your failed Mac computer from external hard drive.
2) After M3 Mac Data Recovery is loaded, please select the failed Macintosh HD and click Next to start the scan.
If Macintosh HD is APFS and encrypted APFS file system, please click "Find Lost APFS Partitions" to recover data from APFS drive.
3) M3 Mac Data Recovery software is scanning the data from the failed Macintosh HD.
4) After the scan completes, please select the found files you want and then click Recover to save them.
After data recovery is successfully done, you can erase the Macintosh HD and reinstall macOS on it.
Solution 3: Restore from Time Machine Backup
If you have a backup of your macOS system, you can restore your macOS system from Time Machine backup with following method:
Step 1: Make sure that your Time Machine backup disk is connected to your Mac computer.
Step 2: Boot your Mac into Recovery Mode.
Step 3: From the macOS Utilities menu, select "Restore From Time Machine Backup" and click Continue.
Step 4: Select your Time Machine backup disk as the restore source and then click Continue.
Step 5: Select a backup and then click Continue.
Step 6: Select the hard disk as the restore destination and then click Restore to continue.
Step 7: Select the hard disk as the restore destination and then click Restore to continue.
Step 8: Restart your Mac computer when the restore is done.
Solution 4: Reinstall macOS in recovery mode
Before reinstalling macOS, please make sure you have recovered all the data from Macintosh HD.
Step 1: Boot your Mac into Recovery Mode.
Step 2: From the macOS Utilities menu, select "Reinstall macOS" and click Continue.
Step 3: Follow the instructions to reinstall macOS.
Solution 5: Erase and then reinstall macOS
The last chance is to erase the drive and then reinstall macOS, but before that, please make sure you have recovered all lost data from unbootable Mac computer.
Step 1: Boot your Mac into Recovery Mode.
Step 2: From the macOS Utilities menu, select "Disk Utility" and click Continue.
Step 3: Select the unbootable Mac hard disk.
Step 4: Choose Erase, complete name, format, scheme, and then click Erase to reformat it.
Step 5: Return to macOS Utilities window in Recovery Mode, and select "Reinstall macOS".
Step 6: Choose the erased Mac hard disk and follow the wizard to complete the installation.
Step 7: Reboot your Mac and then check if your Mac computer can boot.