I have been using Ubuntu 11.10 on my Macbook Air 4,2 for a time now and wanted to upgrade to 12.04. The upgrade process worked flawlessly until the reboot. After rebooting, my boot partition didn't work anymore and now I have to fix that by booting into a live usb stick.
The problem is: No matter what I do, I always end up with a black screen showing
and a blinking cursor beneath.
This screen appears after I select the live usb in refit and press return (or the ubuntu boot partition, or the live usb-copied-to-harddisk-partition). I also get this black boot error screen when I don't use refit but the normal OSX boot manager (by keeping ALT pressed during boot).
Note that I do not get to see any other output; not grub, not the linux loader, not the ubuntu splash screen - nothing except this message.
I tried unetbootin with the normal desktop amd64 iso and the desktop+mac iso, also tried both converted to .dmg with hdiutil, and both with the script that the ubuntu installation instructions suggest.
All of them give me the black
boot error screen.
What can I do to get past this error? What could be the reason for this error?