How to downgrade and not update again?

Hi all,

I'm trying to downgrade to 3.12 for a Kobo Aura.

I do the downgrade, but then I have to setup the device through wifi or a PC and I'm forced to upgrade again one way or another.

I'm sorry if this is somewhere in the forums, but I haven't found anything. Is there any guide on how to downgrade around here or the web?

How can I do the downgrade correctly? I'm trying to return to the FW I had when I bought it (a couple of weeks ago) and I actually don't remember having to update when i booted up the device and connected it to WIFI.

I'm doing a factory reset + connect to pc and copying the FW upgrade folder and files to the .kobo directory.

Any help would be great.

Thanks all.