How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Daniel Your Own Question
Daniel, Mac Genius
Category: Mac
Satisfied Customers: 4770
Experience:  Apple certified on desktop and portable, help desk qualified. Have owned and used Macs since 1989.
Type Your Mac Question Here...
Daniel is online now
A new question is answered every 9 seconds

I had a failed update that locked up. I needed to force shutdown

This answer was rated:

I had a failed update that locked up. I needed to force shutdown with the power button. Now the mac book won't complete the boot process. I got the gray prohibited screen. Booted to the Command S and gets repeating still waiting for root device. I dont have the original disk. What can be done to recover without losing the data?
Hello, my name is Dan.
I will do my best to help you, the only stupid question is the unasked one.

The news I have may not be to your liking but it is the best I can offer.

The good news is that as long as the install DVD has the same or newer OS X than what is on the Mac now you can use it.
Retail is best but a grey disk from another Mac can be used if you have a Mac that will boot from it.

Without having another Mac to use to help repair the damage then an installation disk is necessary.

Until you get a useable OS on the drive the best you can hope for is to use it as an external hard drive.
Hold the letter T when starting up, connect it to another computer (Mac is best) and copy your home folder or the users folder to another location. That will save all your data intact.
Then it means you can do what you need to.

Is that helpful?
Customer: replied 4 years ago.

I remember that the OS was at either 10.5.3 or 10.5.6 before I clicked update. I am updating the computer for one of the elders at my church. I asked if he could find the OS disk and he said he doesn't know where it is. If I download from Apple, what OS should I download? I tried to use a 10.5.6 update disk, but it didn't even boot from that disk when I held C. Are you saying that I need to buy a retail version of the OS?

Apple has no downloadable OSs other than Mountain Lion. Chances are that Mac will not run Mountain Lion.
Is there another Mac and a firewire cable available?
Finding a Leopard retail DVD will be difficult and if found, expensive.

Customer: replied 4 years ago.

Negative. I only have PCs available and no firewire cables.

Then your options are limited. The basic tools needed to fix this are missing.
You said this was for an elder at church, I suggest appealing to the congregation for a Mac user that could help.
I do not know how big the church is but there should be at least 1 Apple techie.
If that person is anything like me they will have all the cables, disks, etc necessary to fix this.
The next best option is having the owner find that install DVD, that is what you need.

Customer: replied 4 years ago.

Well it appears as though it might take time to get a disk. He definitely doesn't know where the disk is located. How to I get back on this support item when get a disk? I don't want to pay twice for this support call.


That is the easy part, just bookmark or make a favorite of this webpage. It will get right back to me.
Once a disk is located or you find hands on tech please let me know.
Customer: replied 4 years ago.

The only disks that I was able to find were 10.4.2 and 10.6. Would either of these help?

Can't hurt, I would try the 10.4.2 first. I am not sure you have an Intel Mac, if so then use the 10,6 disk.

To boot from the installation disc and the Mac is on then start at step #1.

If your Mac is off or will not boot from the hard drive then goto step #3.

1. Insert disc #1, it can be the original that came with your Mac or it can be a retail version newer than the original that came with the Mac.

2. If the disc opens then click on the Install OS X icon, if it does not automatically open then double click the disk icon on the desk top and then click Install OS X.
Your Mac will restart using the install disk.

3. If your Mac is on but will not boot up then insert the installation disk and turn it off by pressing and holding the power until it shuts down.
Now press the power to start it and hold the 'Option' key until the startup manager appears.
If your Mac is off then press the power to start it up, immediately press and hold the 'Option' key for the startup manager.
Insert the disc and click the circle with the arrow to refresh and then select the installation disc to boot from.

Once your Mac is booted from the installation disk the next step is to open Disk Utility.
Click continue at the Language screen, the next screen will be the Welcome to OS X.
At the very top of the screen will be a menubar with 'Utilities', from that drop-down menu select 'Disk Utility'.
There will be a list of hard drives and optical drives on the left of the window, if your drive is in that list then click on it once to highlight.
Now click on the First Aid tab, at the bottom of the Disk Utility window you will see a button called Repair Disk.
Select that by clicking on it. It will either return that everything is okay or that some things were wrong and they were repaired or it found something wrong and it can do nothing about it.
If everything checks out okay or if it does the repairs you then want to repair the permissions.
There will be a button close to the list of drives that says Repair Permissions. Click that to selected and give it time.
There may be a long list of permissions that repairs or there may be only a few.
There will also be some that say SUID that will not be repaired if you have 10.5 or above.
Once you have completed this then you can quit Disk Utility and the installer.
Do Not Install Anything.
Simply restart your machine by selecting it from the menu bar.

Try that.
Customer: replied 4 years ago.

I can't seem to get the mac book to boot from the dvd drive. When I hold option, I do not get the dvd drive as an option.


Sometimes a failed hard drive will cause this.

Two other ways to do it.
Hold the C key and startup.


Opt + Cmd + Shift + Del

Bypass primary startup volume and seek a different startup volume (such as a CD or external disk)

Try those.

Customer: replied 4 years ago.

I tried both and each time I get to the same prohibited sign. I never have any other boot devices to choose from.

One more shot. Remove one stick of RAM and try using the Option key again.
This may have no effect or it may boot.
Next is using another Mac, a firewire cable and Target mode on the sick Mac.
This may let you try repairing the sick drive using the host Mac.
Let me know.
Customer: replied 4 years ago.

Ok... I got it to boot from the DVD by inserting the 10.7 USB drive into the Macbook. I ran the disk utility - repair disk. It does not give me the option to repair disk permissions (button grayed out). I rebooted and it still goes to the prohibited screen.

Ok, that is good so far, now reboot from the USB drive and reinstall OS X. This will give you a new OS but it will do nothing to your data.
Safe it is.
Customer: replied 4 years ago.

The usb is version 10.7. Is that alright?

Yes. That will work.
Customer: replied 4 years ago.

I can't seem to catch a break here. The reinstall shows a screen that states that it needs at least 2 GB of memory. I guess the drive doesn't have that much.

Did you take out any RAM? I did mention doing that, if so replace it and try again.

Customer: replied 4 years ago.

I did not remove it.

Then you will need more RAM. It is cheap, comparatively.
You have not said what Mac you have so I will let you sort that out. Once you match what you have then get as much RAM as you can (more is better).

Then try again. Please keep me posted.
Daniel and 2 other Mac Specialists are ready to help you
Customer: replied 4 years ago.

I bought more ram and tried to install 10.7. The install would not let me go from 10.5 to 10.7 so I inserted the 10.6 disk and it was recognized finally. I installed 10.6 and it booted and all of the data was there. Thank you so much for working with me on this issue.

Happy to have been of service. Not all Intel Macs will run Lion or Mountain Lion, my MBP won't.
It does run 10.6.8 nicely though.
I do suggest updating and repairing permissions, this will help keep things out of trouble.
You are welcome.

Related Mac Questions