I'm currently on page 18 and haven't found anything yet. I've seen the black screen problems but not with a failed boot. If I can't figure it out, I'll post results of going into Ubuntu chroot.
It is along the lines of having "no image file or partition specified." and there is no directory in /media/mmc1/ubuntu.img though I know the file is actually in MyDocs. I might try copying it to the card and rebooting and hoping for it to work.