This Idiot Needs Help...

[gthorson]

So I was excited to install El Capitan Beta 4. On my first Mac, I installed through Apple's sign-up program and all went fine (although only through Beta 3), but on the second one, I downloaded Beta 4 directly using a link posted here on MacRumors.

Big mistake! First, I didn't realize until the thread below that I could just click on the App Store...Purchased tab and download it on my second and third Mac. Rather, I used the direct link posted here on MacRumors to begin directly downloading first the firmware and then the fourth beta.

Now I can't get my second Mac to behave. It originally would just power off about 40% through the restart process. Now I've created a bootable drive through my WD Passport external drive. But I still can't load my backup, erase my second Mac drive, or load Yosemite on it via the web. It tells me it is unable to unmount the drive.

Any suggestions?

 

[comics addict]

So your saying that you have not been able to use the recovery partition to reinstall OS X or, if worse, erase the internal drive and clean install OS X ?

 

[gthorson]

So your saying that you have not been able to use the recovery partition to reinstall OS X or, if worse, erase the internal drive and clean install OS X ?

Exactly. It won't let me erase or repartition the hard disk. The error message is that it failed to unmount the drive.

 

[comics addict]

I think your best bet would be to boot from a external drive that can run recovery or install OS X. Now if you can't even create it from your boot volume I'm afraid I can't help you beyond referring you to an Apple store.

 

[gthorson]

I think your best bet would be to boot from a external drive that can run recovery or install OS X. Now if you can't even create it from your boot volume I'm afraid I can't help you beyond referring you to an Apple store.

So I booted from an external drive with El Capitan beta 3. Everything works well, except Disk Utility won't allow me to reformat the drive, either. I'm trying to install Yosemite on the external drive now to see if it works to boot from it.

 

[benthewraith]

So I booted from an external drive with El Capitan beta 3. Everything works well, except Disk Utility won't allow me to reformat the drive, either. I'm trying to install Yosemite on the external drive now to see if it works to boot from it.

In the Yosemite installer, run Terminal and find the id for the logical volume group and copy it. If you're trying to erase the whole drive, it will be the first option listed.

You can find it by running "diskutil cs list" without quotation marks.

Then the command to delete it is "diskutil cs delete [logical volume group # pasted here without brackets]

Should clear the drive.

 

[dianeoforegon]

Exactly. It won't let me erase or repartition the hard disk. The error message is that it failed to unmount the drive.

I've seen this with a dying drive. Nothing from repairing drive, to trying to reinstall OS X would work Eventually got a clone to boot and did a restore. First reaction was great then first restart got a kernel panic. Future boots all failed.

 

[gthorson]

I've seen this with a dying drive. Nothing from repairing drive, to trying to reinstall OS X would work Eventually got a clone to boot and did a restore. First reaction was great then first restart got a kernel panic. Future boots all failed.

I finally caught a break. After loading from Yosemite installed on an external drive, it allowed me to erase the disk. Then I installed El Capitan correctly.

Thanks to everyone for your help!