https://support.apple.com/en-gb/HT211683
- Power on Mac holding down Command - R or Option key
- From menu access Dick Utility
- Reformat Hard drive and rename it ‘Macintosh HD’
- Power down Mac
- Insert El Capitan bootable US stick
- Power on Mac holding down Option key
- Choose USB disc icon and proceed with installation
- Once installed use Apple Updates to update Mac
- Once fully updated you will be prompted to download Safari Safari 11.1.2
Notes
- Safari 11.1.2 is the highest version for El Capitan 10.11.6
- Shipped OSX for iMac (Late 2012) is Mountain Lion
- Installation can be done directly with El Capitan bypassing the need to install Mountain Lion
- If errors occur during installation. Remove the Ram leaving one Ram module installed in the bay.
- Cmd-D will not work as El Capitan is not supported.
- Download Java 7 for El Capitan
If you get this error 'This copy of the Install OS X El Capitan application can't be verified. It may have been corrupted or tampered with during downloading' The date maybe wrong.
In terminal type: date 1001010115
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Code to make El Capitan bootable USB drive with Terminal
sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/el-cap --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app --nointeraction







