I think the only significant change is in /etc/inittab. All other changes are made within an XCSoar directory
Original
Code:
# This is run first except when booting in single-user mode.
::sysinit:/etc/init.d/rcS
::respawn:/sbin/getty -L ttymxc0 115200 vt100
::ctrlaltdel:/sbin/reboot
::shutdown:/bin/umount -a -r
::restart:/sbin/init
XCSoar
Code:
#
# XCSoar Glide Computer - http://www.xcsoar.org/
# Copyright (C) 2000-2015 The XCSoar Project
#
# This inittab has been installed by XCSoar. It launches a menu that
# allows the user to choose between XCSoar and Nickel (the original
# Kobo software)
::sysinit:/opt/xcsoar/bin/rcS
::ctrlaltdel:/sbin/reboot
::shutdown:/bin/umount -a -r
::restart:/sbin/init
If you're comfortable with linux, mount the SD card on a linux (or possibly Mac) and edit the /etc/inittab on the SD card to put back the Kobo content.