Q: I have tried to upgrade my iMac 21.5" mid-2010 to El Capitan. It is now "hung" at 27 minutes remaining on the installation. It never completes, it just gives off an alarm beep and restarts. What can I do?

Hello,

Please start by doing the following:

- disconnect all USB, firewire peripherals etc (except keyboard and mouse) and see if that solves it. If not:

- perform a SMC reset: Reset the System Management Controller (SMC) on your Mac - Apple Support

- perform a PRAM reset: OS X Yosemite: Reset your computer’s PRAM

Did this solve it?

there are instances where OS X will not appear to finish the install but actually has. In that event rebooting seems to rectify the issue.

If you do have a Time Machine backup you can restore from that.

However neither of these are the case (e.g. you DON'T HAVE a backup) I suggest trying to boot into target mode, connecting to another Mac, getting what you can off the hard drive then restoring your computer to the disks it came with (Internet recovery is not an option on the 2010 iMac) and then go back and try OS 10.11 if you feel your initial image was the problem.

OS X Mountain Lion: Transfer files between two computers using target disk mode

Hello again,

the -2002F points towards network connection issues. This will likely also explain why the install went bad.

If your mac has the option to connect an Ethernet cable, please go ahead and connect one between your computer and your modem. See if the install continues with this setup. If it doesn't, try Internet Recovery again with the Ethernet cable connection.

Insert the installer CD or DVD that came with your computer

unplug the computer from the power outlet

wait 30 seconds

insert the plug back into the outlet

reboot and hold down the OPTION key while it start up

Choose the CD or DVD as the boot device

when the installer process begins choose the disk utility and format the drive Mac Extended (Journaled)

reinstall the OS

I have several things for you to attempt:

When you did the SMC reset, did you unplug ALL peripherals during it, and since?

Also, use the instructions on this page to boot to Single User mode and run fsck (repair of partition table and harddrive check): http://www.everythingmacintosh.com/tech-notes/repair-your-hard-disk-in-single-us er-mode/

If none of this solves anything, start your computer in verbose mode and when it get's stuck, send a clear picture of what's on screen:

https://support.apple.com/en-us/HT201573

Hold down Command-V for verbose mode.

This mode foregoes the apple logo + loading bar overlay and shows you in text form what the computer is performing while it's booting. Maybe you'll see something useful.

to remove a stuck CD restart the computer and hold down the mouse button. The CD will eject.

It sounds like your HD may have died or is dying, unless you were able to reboot to the OS the CD installed on you. Sometimes it gets to a few minutes remaining and it actually has like close to an hour unpacking all these little files.

If you can pop the disk out check it for blemishes, fingerprints, scratches and if you have a lint free cloth (for glasses or LCDs) start at the center, wipe straight out to the edge, clean the disk, just don't Mr. Myiagi it with a shammy.

for the HD see this video as to what is involved (OWC sells IMHO great parts and they have been cited by other members of this community as "knowing what the **** they're doing when it comes to macs".)

https://www.youtube.com/watch?v=Zjq6uLy-2cI

it may also be possible to install the OS on a USB hard drive. While this may not be ideal for speed it might get you a working computer while you are in the dark figuring out the next step.

also strange as it may sound try removing any 3rd party RAM and just use the RAM that came with your computer when you purchased it, if this is the case. Sometimes this voodoo works but as to why I can't give you a definitive answer.