Q: Imac 27" 10.11.3 suddenly won't recognize Icloud password

Since it is in warranty why don't you take it to the Apple Store for repair. If the drive has failed it will be replaced free of charge.

There are three ways to reinstall OS X. The first way is to re-install over the existing system (must be the same version) which does not erase the drive. The second way erases the drive and reinstalls the original version of OS X that was pre-installed. This does not work if the computer was released prior to 2011. The third way is for older machines pre-2011 on which you must first install Snow Leopard after erasing the drive.

You do not have Lion installed as shown in your profile if you have an iMac that is only 7 months old.

Reinstall El Capitan Without Erasing the Drive

Make sure you have a current backup before proceeding.

 

Boot to the Recovery HD:

 

Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears.

 

Repair

 

When the recovery menu appears select Disk Utility and press the Continue button. After Disk Utility loads select the indented Macintosh HD entry from the the left side list.  Click on the First Aid tab in the toolbar.. If Disk Utility reports any errors that have been fixed, then re-run First Aid until no errors are reported. Wait until the operation completes, then quit Disk Utility and return to the main menu. Select Restart from the Apple menu.

 

 

Reinstall OS X: Select Reinstall OS X and click on the Continue button.

 

Note: You will need an active Internet connection. I suggest using Ethernet if possible because it is three times faster than wireless and more reliable.

Install or Reinstall OS X from Scratch

Be sure you have backed up your files because the following procedure will remove everything from the hard drive.

 

Boot to the Recovery HD:

 

Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears.

 

Erase the hard drive:

 

  1. Select Disk Utility from the main menu and click on the Continue button.

 

  2. After DU loads select your startup volume (usually Macintosh HD) from the

      left side list. Click on the Erase tab in the DU main window.

 

  3. Set the format type to Mac OS Extended (Journaled.) Optionally, click on

      the Security button and set the Zero Data option to one-pass. Click on

      the Erase button and wait until the process has completed.

 

  4. Quit DU and return to the main menu.

 

Reinstall OS X: Select Reinstall OS X and click on the Install button.

 

Note: You will need an active Internet connection. I suggest using Ethernet if possible

           because it is three times faster than wireless.

 

This should install the version of OS X that you had installed.

It sounds like the structure of your Fusion drive is corrupt.

Paste this into the Terminal, hit return and post the results…

diskutil list

Have you tried this method:

Install OS X Using Network Recovery

Be sure you have backed up your files because the following procedure will remove everything from the hard drive.

 

Boot to the Network Recovery Server:

 

Restart the computer and after the chime press and hold down the COMMAND-OPTION- R keys until a globe appears on the screen. Wait patiently - 15-20 minutes - until the Recovery main menu appears.

 

Partition and Format the hard drive:

 

1. Select Disk Utility from the main menu and click on the Continue button.
2. After DU loads select your newly installed hard drive (this is the out-dented entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.
3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Apply button and wait until the process has completed. Quit DU and return to the main menu.

 

Reinstall OS X: Select Reinstall OS X and click on the Continue button. Be sure to select the correct drive to use if you have more than one.

 

Note: You will need an active Internet connection. I suggest using Ethernet if possible because it is three times faster than wireless.

 

This should restore the version of OS X originally pre-installed on the computer.

Please try this before fooling around with the the drive via the Terminal. Destroying a Fusion drive structure is not particularly easy, so it just doesn't happen.

Kappy wrote:

 

Please try this before fooling around with the the drive via the Terminal. Destroying a Fusion drive structure is not particularly easy, so it just doesn't happen.

The terminal command just prints out the structure to see if it's corrupted. And it can be damaged easier than one might think. For example trying to add two partitions, or re-partitioning it more than once, or removing a Boot Camp partition incorrectly. There are others.

Same problem here. Wait for an Apple specialist to reply. Not someone who has no idea what they are doing to give you advice.

kerbeg wrote:

 

Same problem here. Wait for an Apple specialist to reply. Not someone who has no idea what they are doing to give you advice.

Seeing this is a user to user forum and there are no "Apple Specialists" here. Users would have a very long wait indeed and would be no point to these forums.

Sorry, posted to the wrong place.

I'm not sure how TDM comes into this. You would need two computers. Each could have Firewire ports or Thunderbolt ports. Adapters can be used for Thunderbolt to Firewire. Connect the two and boot the target machine into Target Disk Mode. Boot the other normally. Not sure what you think you would do at this point.

Nevertheless, doing a Network Restore will erase the drive, so you needn't worry about overwriting El Capitan. Mountain Lion can be upgraded back to El Capitan. But you would know that had you read what I posted. You would note that re-partitioning the disk drive was the first thing you would do. Perhaps the next time around you could post a much clearer statement of your problem. Then we don't have to guess what you want.

If you have a bootable Recovery HD, then you can do a clean install:

Install or Reinstall OS X from Scratch

Be sure you have backed up your files because the following procedure will remove everything from the hard drive.

 

Boot to the Recovery HD:

 

Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears.

 

Erase the hard drive:

 

  1. Select Disk Utility from the main menu and click on the Continue button.

 

  2. After DU loads select your startup volume (usually Macintosh HD) from the

      left side list. Click on the Erase tab in the DU main window.

 

  3. Set the format type to Mac OS Extended (Journaled.) Optionally, click on

      the Security button and set the Zero Data option to one-pass. Click on

      the Erase button and wait until the process has completed.

 

  4. Quit DU and return to the main menu.

 

Reinstall OS X: Select Reinstall OS X and click on the Install button.

 

Note: You will need an active Internet connection. I suggest using Ethernet if possible

           because it is three times faster than wireless.

 

This should install the version of OS X that you had installed.

If you wish to simply reinstall El Capitan, then do the following:

Reinstall El Capitan Without Erasing the Drive

 

Make sure you have a current backup before proceeding.

 

Boot to the Recovery HD:

 

Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears.

 

Repair

 

When the recovery menu appears select Disk Utility and press the Continue button. After Disk Utility loads select the indented Macintosh HD entry from the the left side list.  Click on the First Aid tab in the toolbar.. If Disk Utility reports any errors that have been fixed, then re-run First Aid until no errors are reported. Wait until the operation completes, then quit Disk Utility and return to the main menu. Select Restart from the Apple menu.

 

Reinstall OS X: Select Reinstall OS X and click on the Continue button.

 

Note: You will need an active Internet connection. I suggest using Ethernet if possible because it is three times faster than wireless and more reliable.

None of those can happen spontaneously. A Fusion drive does not suddenly stop being a Fusion drive. It can have a damaged directory, but it doesn't simply become something else. In any event my post was suggesting to try something first. If it fails, then the problem is all yours. What i know about Fusion drives is admittedly little, but I have broken them into separate drives and put them back together as Fusion drive. A bit more difficult than partitioning them. As for Boot Camp I am happy to leave that to Loner T.

The point of it all is unless a user is familiar with using the Terminal with diskutil, I think that if there is an easier solution using Disk Utility, then better to do that instead. But that's my opinion. It was not my intent to start a debate over this.

Kappy wrote:

 

None of those can happen spontaneously. A Fusion drive does not suddenly stop being a Fusion drive. It can have a damaged directory, but it doesn't simply become something else.

Nothing can happen spontaneously without a user's action. I never said or implied that.