Terrence Jeffrey Santos

I've gone through instructions step by step multiple times on 2 different 5D mk iii's with different sd and cf cards and am getting the same result which is "enable boot disk :)"   To which I power off the cam and power back up, hit trash can and nothing.   Throughout the process I have noticed that firmware "1.1.3-ml-v2.3.next" does not stick. I will get to step one of the instructions on the EOS guide but when I come back to step 2 I see the firmware reverts back to the canon 1.1.3   Any suggestions on what I'm doing wrong?

Andrew I got this far in the install but when I powered down and powered back on I still wasn't getting the menus to come up when I hit the trash can. I just had an empty frame with my grid and focus box.   Any ideas?