I'm having this bootflag issue, too. I had the official Alpha 3 running fine. When I tried to install a nightly build to get the RAW module working, things went awry. When I turn it on, it soon announces the loading of the bootflag along with a smile. The firmware reads as 1.1.3-ml-v2.3.NEXT. When I hit the Trash button, no Magic Lantern menus come up.
I wouldn't mine not being able to uninstall the flag, if Magic Lantern was working, but it's not.
Anyone out there who has this bootflag issue, but has Magic Lantern working?
UPDATE: I kept fiddling (worried about bricking camera with each step), but finally got everything working.
Steps I took:
1) I deleted all the ML files from the SD card. and replaced them with the official 5diii alpha build files.
2) I started up the 5diii with the Alpha 3 on the SD card. The Alpha 3 ML started working again on the 5diii.
3) Then I copied Canon firmware 1.1.3 onto the SD card. I was able to 'update' the 5diii firmware to 1.1.3. (i don't remember every step in that or if there were any issues).
4) then i carefully followed the guide at planet5D -- http://www.cinema5d.com/news/?p=17898
5) and it worked. the bootflag issue disappeared!
CONCLUSION: I think tried to simply update the Alpha 3 to the latest build. Maybe this is what's been happening to others. Good luck!!
I wouldn't mine not being able to uninstall the flag, if Magic Lantern was working, but it's not.
Anyone out there who has this bootflag issue, but has Magic Lantern working?
UPDATE: I kept fiddling (worried about bricking camera with each step), but finally got everything working.
Steps I took:
1) I deleted all the ML files from the SD card. and replaced them with the official 5diii alpha build files.
2) I started up the 5diii with the Alpha 3 on the SD card. The Alpha 3 ML started working again on the 5diii.
3) Then I copied Canon firmware 1.1.3 onto the SD card. I was able to 'update' the 5diii firmware to 1.1.3. (i don't remember every step in that or if there were any issues).
4) then i carefully followed the guide at planet5D -- http://www.cinema5d.com/news/?p=17898
5) and it worked. the bootflag issue disappeared!
CONCLUSION: I think tried to simply update the Alpha 3 to the latest build. Maybe this is what's been happening to others. Good luck!!