"There are several ways to uninstall Magic Lantern on the 5Dmark 2, but none of them worked for me. None of the solution on Youtube worked. The green text did not show up, and it was not possible to use the menu on the camera to update or format the card so ML could disappear. The solution was to install ML again to the CF card: I created a new folder on the PC. Here I uploaded all the files from the ML -> "Download Magic Lantern -> Stable Release: v2.3" to the new folder. So I transferred the ML files to CF who stood in the PC. When the PC will ask if any of the files on the CF card Schall be replaced? (since they are already there) Answer yes to all those questions. Insert the CF back in the camera and turn it on. Then the green text will up and ML can be uninstall, as shown in many yotube uninstall guides."
This is so true. I am on ML nightly build on a 5D2 and when I click on the Canon firmware update button, nothing happens.
So I just have to format a new card and load ML v2.3 onto it and then click the Canon firmware update button. This time, I was
able to see the ML screens and reset the boot flag. Thank you for the tip Geir!