Resetting the password using Target Disk Mode

Question

Resetting the password using Target Disk Mode

My friend has a 2010 Mac Pro that she has locked herself out of. It is currently running Mac OSX Mojave. The video card currently in the Mac Pro is an upgrade and not flashed with an Apple bois. So no Apple logo and no recovery screen. She did have the orginal video card, which she swapped out the upgrade one, but nothing came on the screen after the post chime, and so we think the original video card is toast.

I have a 2012 Macbook Pro and will be checking out her Mac Pro the next time I'm in town (several states away).

Will the following scenero work? Connect the Mac Pro to the Macbook Pro via FireWire 800. Boot the Mac Pro into Target Disk Mode by holding T on the keyboard while booting until I see it come up on the Macbook Pro's desktop as an external drive. Reboot the Macbook Pro and hold CMD+R to go into recovery mode. Under utilities go to Terminal and type resetpassword to bring up the passwrod reset screen. Find her user name (hopefully) from the list and reset it that way?

The only other option would be for me to purchase a used video card that is native to Apple and hope that it works, but if the above steps do the same thing, it would save me time and money.

Earlier Mac models

Posted on Jul 13, 2025 06:13 PM

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Answer 1

HWTech

Level 9

66,716 points

Jul 14, 2025 01:10 PM in response to DeathStalker13

I don't think that will allow you to reset the password since the "broken" Mac will just appear as an external drive.

You can instead delete the "<mount-point>/var/db/.AppleSetupDone" file on the broken Mac & reboot the broken Mac which will trigger Setup Assistant to create a new admin user account. You can then easily change the password of the main user account. Just make sure to delete the file on the "external" drive (aka the broken Mac in Target Disk Mode).

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Answer 2

HWTech

Level 9

66,716 points

Jul 15, 2025 08:19 AM in response to DeathStalker13

DeathStalker13 wrote:

I’ll check that. I think the account she currently has locked is an admin account as well. Would a new admin account be able to reset the password of a second admin account?

Yes. Which is why I suggested it. See the following Apple article for details of that aspect of the process:

Change or reset the password of a macOS user account in macOS Mojave or earlier - Apple Support

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Answer 3

Jul 13, 2025 07:31 PM in response to DeathStalker13

You indicate that her new video card's firmware has not been updated to let it work in a Mac, and that her old video card appears to be "toast."

So let's say that you reset her password. How, then, is she going to use that Mac Pro? She'll still have a video card that needs a firmware upgrade and another video card that is toast. Or are you saying that the new card which does not have the right firmware works – just not at startup time?!?

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Answer 4

Jul 14, 2025 04:00 AM in response to Servant of Cats

The newer card works perfectly except for showing the Apple logo or the Recovery menu.

when she starts it up, the Mac Pro will chime. Then after it fully boots up, the first thing she sees is the sign in screen. When she was able to log in, everything worked and no video issues.

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Answer 5

Jul 15, 2025 07:36 AM in response to HWTech

I’ll check that. I think the account she currently has locked is an admin account as well. Would a new admin account be able to reset the password of a second admin account?

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