iMac (Mid 2010): iMac shuts down or stops responding during startup

Under certain circumstances, your iMac (21.5-inch or 27-inch, Mid 2010) computer my not start up properly. The iMac (Mid 2010) may shut down or stop responding during the startup sequence. The computer may display a gray screen with an Apple logo, and a  gray progress bar that may complete before the computer shuts down. The hard drive may not be recognized or appear to be unrepairable when you run Disk Utility (located in the Utilities folder) and attempt to verify or repair the volume.

This article has been archived and is no longer updated by Apple.
  1. Download and install iMac Hard Drive Firmware Update 1.0 using Software Update. This will install an updater application in the Utilities folder; if the update doesn't run automatically, double-click the updater application in the Utilities folder.  
  2. Follow the onscreen instructions to install the firmware update. Important: do not interrupt power to the computer while the updater is running.
  3. When the computer restarts, the update should be installed successfully.  

If this issue occurs after installing the update on your iMac (Mid 2010) and Disk Utility continues to report that the volume cannot be repaired, the hard drive may need service.

If you cannot start up the computer normally to install this update, you can temporarily use an external hard disk drive (with the version of Mac OS X that came with iMac (Mid 2010) installed on it) and run Software Update.  

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