I installed Ubuntu 12.10 on my MacBook Air, first gen, removing Mac OS X. The OS has gotten really screwy since the battery died while installed OS updates. So I wanna format the laptop and install Ubuntu on it again.
I tried booting the laptop and pressing alt to choose the bootable Ubuntu 12.10 USB key, but not a single boot option appears.
How can I boot into my USB key to reinstall Ubuntu on the laptop?