

When erasing the drive make sure to select the whole physical drive within Disk Utility and erase the physical drive as GUID partition and MacOS Extended (Journaled). Macs are very picky about the drives used for booting a Mac plus the quality of many USB sticks is extremely poor so try using another USB stick especially a different brand. dmg file you can then proceed to use the command line to create the bootable macOS USB installer itself. Make sure to carefully read the section regarding macOS 10.11 as there are extra steps required to extract the real installer from the downloaded. Here are the instructions for creating a bootable macOS USB installer: Mac Os El Capitan Iso Mac Os El Capitan Bootable Usb Windows
HALO COMBAT EVOLVED MAC OS X ISO INSTALL
Are you trying to boot into Recovery Mode to install macOS to an external USB drive or are you trying to boot from a macOS USB installer to install macOS to the internal drive? I'm a bit confused by your post on what you are trying to do here. Alternatively, you can just hold down the C key while starting up to boot directly into the USB drive. Wait until the Startup Manager pops up, then select the 'OS X Base System' volume. To install El Capitan, make sure the USB drive is inserted into the computer, then restart the computer while holding the Option (alt) key on your keyboard. Press the spacebar and select Boot Mac OS X in verbose mode. Use the arrow keys to select Boot OS X Install from Install OS X El Capitan (It should be selected by default).

Restart your computer and boot from the USB drive (Press Esc/F8/Del to access the boot selection menu). Decided to do another clean install but MBP won't boot from USB and uses the recovery version instead.

Decided to use migration assistant, most apps not working plus all the clutter from pre clean install. Booted from it, erased my MBP (mid 2009), clean install from USB installer. Created a bootable USB with El Capitan installer.
HALO COMBAT EVOLVED MAC OS X ISO SOFTWARE
The ISO Files for a software system are those that can be burned into a bootable DVD and then they can use the DVD to install the particular Software or Operating system on ones PC/Mac/MacBook.
