The easiest way to launch custom scripts, change hidden settings, and run actions on Kobo eReaders.
You can download pre-built packages of the latest stable release from the releases page, or you can find bleeding-edge builds of each commit from here.
After you download the package, copy KoboRoot.tgz into the .kobo folder of your eReader, then eject it.
After it installs, you will find a new menu item named NickelMenu with further instructions which you can also read here.
To uninstall NickelMenu, just create a new file named uninstall in .adds/nm/, or trigger the failsafe mechanism by immediately powering off the Kobo after it starts booting.
Most errors, if any, will be displayed as a menu item in the main menu in the top-left corner of the home screen. If no new menu entries appear here after a reboot, try reinstalling NickelMenu. If that still doesn't work, connect over telnet or SSH and check the output of logread.
@NiLuJe's toolchain and sysroot are required to compile NickelMenu. They can also be found as a Docker image. To compile NickelMenu, just run make all koboroot with the toolchain in your PATH, or use docker run --volume="$PWD:$PWD" --user="$(id --user):$(id --group)" --workdir="$PWD" --env=HOME --entrypoint=make --rm -it geek1011/kobo-toolchain all koboroot with the Docker image.