Haven't created a dual boot N9 for a number of years now, but would read the WiKi:http://wiki.maemo.org/Ubiboot

Do you mean that you can't setup developer mode upon a recently reset N9? Have you installed? https://openrepos.net/content/ancelad/n9-repomirror

Please note that there can be problems installing this application upon certain regions firmware, which may necessitate choosing a different image.

Helpful illustrations and valid "Sillyboot" link here:https://n900-indonesia.blogspot.co.u...-nokia-n9.html