Tried the koboRoot.tgz from the release, but the Kobo is still the same

[lantennec]

Hi
Not knowing about mounting codes, I thought I'd follow the steps, copying the koboroot.tgz into the .kobo folder, eject and let the kobo update and then I'm supposed to have the choice to open it in kobowriter mode.
When doing this, the Kobo seems to update (there's a icon "do not turn off) but then I have no choice, it turns on the same Kobo front page as usual...
I bought a kobo glo HD to do that, I have the keyboard and the cables etc. but the Kobo stays the same
Is there anything else to do ? Did I do it with the wrong file ??
Thanks