Bootmii boot2 normally installs with Homebrew channel using the hackmii installer, not when cIOS are loaded.
A DVD slot flash on start up can mean that bootmii is installed as boot2. Bootmii works off the files and not buttons like preloader. If bootmii is installed and the files are on your SD then you either have no bootmii boot2 or it doesn't like your SD card - it's pretty fussy.
It's also possible you don't have a modchip, it could just have been cIOScor, which no longer exists because you changed system menu.
Try a different SD and see if you can get bootmii.