syscheck is a homebrew, and it requires The Homebrew Channel (HBC) to be installed first.
replacing the "boot.elf" with the boot.dol will not work, even if renamed, even if compiled as elf and not converted as dol, because hackmii installer is using a vulnerability to get hardware rights (AHB access), which all other homebrew are not doing.
All other homebrew are relying on HBC to provide AHB, they are not elevating the rights themselves.
I don't know what the issue is.
Try a different SD Card (even an SDHC if you don't have another SD non HC)
Be sure it's not write protected, because it needs to write files to it.
Could you tell when that crash happens? at install, at verification screen?
do you see the screen "press 1" ?
do you see the selection screen telling you to choose what to install ?