I tried everything I could on my Macbook Pro Model: MacBookPro6, Intel Core i5, Boot ROM MBP61.0057.B0F SMC 1.57f18.
First I installed rEFit then I downloaded 'ubuntu-12.04.2-desktop-amd64+mac.iso', then converted it into
hdiutil (with format UDRW), then I loaded it into the USB key using
dd. After reboot... nothing.
Even if I press C, it doesn't load, it doesn't work even with rEFit, what's wrong? How can I get rid of OSX and have my Ubuntu running on this machine?