Create bootable Diagnostic USB from multiple .DMG's?

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Create bootable Diagnostic USB from multiple .DMG's?

I would like to create a bootable Diagnostic USB for a MacBook Pro 9.1. running Catalina 10.15.7

I downloaded 022-5879-A.dmg (which is the AHT for this specific MBP) and created a bootable USB using:

cp -r /Volumes/AHTCTwo/System /Volumes/Sandisk/
sudo bless --folder /Volumes/Sandisk/ --file /Volumes/Sandisk/System/Library/CoreServices/.diagnostics/diags.efi --label AHT

But booting while holding Option and selecting the USB EFI to boot from did not do the trick. A series of kernel text (white text with black background) flashed by during boot and the system booted from the primary drive.

Now I understand that due to an Apple bug in newer firmware updates included with the 9,1.Macbook Pro it is not compatible with this AHT and needs Apple Service Diagnostic (ASD) found here: Apple Service diags 3s155.

The problem is that this 3s155 is 4 .dmg files of 700 mb each.

How can I create a bootable USB from 4 .dmg files using the terminal?

I'd appreciate an answer suited to a terminal usage beginner.

Thanks!

MacBook Pro 15″, macOS 10.15

Posted on Apr 19, 2023 7:55 PM

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Answer 1

HWTech

Level 9

68,732 points

Apr 22, 2023 6:52 PM in response to Gold333

First of all you cannot copy the AHT to a volume to make it bootable. If this is indeed a bootable AHT .dmg image, then you will need to use the Disk Utility "Restore" option. Make sure the external drive USB is partitioned as GUID and the volume is MacOS Extended (Journaled).

The same holds true for the multi-part .dmg's. Disk Utility will automatically utilize each .dmg in turn, just select the first image in the group to "Restore".

Those .dmg files should contain a .pdf file or other type of README file which should contain instructions on how to make a bootable USB drive.

Many times the "Restore" may fail with an error regarding needing to run "asr" on the image file. If this happens, then you will need to initiate the "asr" scan of the .dmg by locating the "asr" option on one of the Disk Utility menus. After running the "asr" scan, then you should be able to use Disk Utility to "Restore" the image onto the USB volume.

Usually you can select the destination to any HFS+ volume on a USB drive/stick.

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Create bootable Diagnostic USB from multiple .DMG's?

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