I recently pulled my old MacBooks 2009 out of the closet. Not sure what the exact model is, but anyways, a few years ago I spilled water on the keyboard, so most of the keys don't work anymore. (Sadly the special keys don't work either, like option, command, and control.) Before I stopped using it, I wiped the internal drive, for security purposes.
But now I need OS X for certain work I am doing (Objective C programming for a large scale project,etc). I have the DMG file, which I had on a backup, for OS X El Capitan. I used my Ubuntu machine to convert the DMG to an ISO, and then put then burnt OS X on to a USB. I plugged it in to the macbook, started it up, held down the option key (on an external keyboard) and it didn't work. Any idea on how to fix this would be highly appreciated!