iMac won't boot from USB, white screen + cursor
Hi I have 3 iMac late 2009 A1311, I bought them without operating system, they have hard drive and ram
I made a USB bootable device with el capitan but when I try to boot holding the option key at startup I only get a white screen with cursor that can only move up and down directions.
All the other startup keys give me only a folder with question mark ( command + R, command + s...)
any help please ?