2009-12-24 12:36 - edited 2011-02-09 11:04
If you have tried to reset an N900 from the settings menu on the device, you would have noticed it would have left all your data intact.
Sometimes you want to start from scratch and delete all data in one go.
Here is how you do it.
Its quite extensive, but comprehensive.
From a windows PC
You first need to download three pieces of software.
The first software you need is called "Maemo Flasher", and this is the program that needs to be installed on your PC and can be found here:
http://tablets-dev.nokia.com/maemo-dev-env-downloa
Download the latest version of Maemo Flasher (which is currently 3.5 at time of posting this), and make sure you download the .exe file (maemo_flasher-3.5_2.5.2.2.exe).
Install that file.
Next you need the software for the N900 itself.
That can be found here:
http://tablets-dev.nokia.com/nokia_N900.php
This page will ask you to enter your IMEI, with very clear instructions on where to find it.
Follow the on screen prompts until you reach the download section.
There are two pieces of software you need to download from there.
There are, unfortunately, 3 different names for the OS.
Latest version is "PR 1.2 version 10.2010.19-1".
Download the latest eMMC package available, It's version 10.2010.13-2.
The OS is a little more difficult to figure out which one you need.
The notes alongside the software lets you find the right package easier.
I found the best way to check is to do the following: (On the N900)
This will show you this image(or similar)

Note the Version number on your N900's screen.
Download the OS package that matches the Version on your device. As shown in the image above, using the red text as an example.
For people that purchased the N900 in the UK, the OS package will probably be the same as the red text. But make sure you check.
Software downloads complete.
Place these two software packages in the following location on your PC.
c:\program files\maemo\flasher-3.5
You should now have two .bin files in the directory above.
Next steps.
Updating the N900 OS

Resetting the Mass Memory
This image below shows the completed reset of the eMMC (32GB HDD), in the command prompt on your PC.

This would have now removed any data you had stored there. Including Music, Photos, Contacts, SMS..
The complete reset of your N900 is now complete.
I hoped this has helped.