Reset N900 – Flashing back to original state

I had been playing with multiboot, custom kernels and nitdroid on my N900, and so it happened, that the basic way to upgrade from Fremantle 1.2 to 1.3 did not work. It complained that I had too little memory available etc. This may have happened to you, too. In this case, only way to upgrade is to flash the system and memory using factory state images. This is also a quick and moderately easy way to get rid of all the junk that you have installed on your phone.

What you need:

• N900 USB cable (micro-USB to USB)
• Internet connection to acquire flasher application and images
• IMEI code of N900
• A bit of command line skills

Download application and images
Make a new directory and put all that you download into that directory.

First go to this site to download flasher application. Accept the disclaimer and then you will see list of files. Download one of the maemo-flasher-3.5 files depending on what operating system you are using on your PC. If you are using Ubuntu or other Debian derivatives, then download .deb package. There is also a general Linux package, OS X package and Windows package.

Notice! flasher-3.5 supports only x86/32-bit architecture!


BTW, there is also an interesting virtual image of complete Ubuntu Lucid with preinstalled SDK tools for N900 Fremantle 1.3 development available. You can use it with VMWare Player.

Then you should go to another site to download system images. First you are asked the IMEI code. Just write it where asked, then accept the disclaimer. Now you will see a list of files. You will need two files: eMMC and Maemo system. There are several versions available, not only PR 1.1, 1.2 and 1.3 but also regional variants of these. Pick the one which is appropriate for you.

As an example:
RX-51_2009SE_10.2010.13-2.VANILLA_PR_EMMC_MR0_ARM.bin eMMC content 10.2010.13-2
RX-51_2009SE_20.2010.36-2_PR_COMBINED_MR0_ARM.bin PR 1.3 version 20.2010.36-2 Latest Maemo 5 Global release for Nokia N900

Install flasher
First you need to install the flasher application. Go to the directory where you saved the files you downloaded above. On command line run (replace VERSION-NUMBER with the version number of package)

sudo dpkg -i maemo-flasher-VERSION-NUMBER.deb

Now you are ready to flash your N900. Read the following instructions carefully before you do anything!

Flashing eMMC and Maemo
eMMC has to be flashed first. Afterwards Maemo system is flashed separately. This will wipe out everything you have installed and configured in internal memory. Removable memory card is not affected. So, BACK UP ALL DATA in internal memory, like pictures, videos, documents etc. Once this is done, you may proceed.

1. TURN OFF the phone

2. Connect USB cable into computer, but NOT INTO N900 yet.

3. Slide the keyboard open in N900, and PRESS U (key U) AND KEEP IT PRESSED.

4. While pressing U, CONNECT micro-USB INTO N900. DO NOT DISCONNECT USB cable until said so.

5. Soon N900 will turn on by itself. When you see Nokia logo (it may be quite dim) and little USB logo on corner of screen, you may RELEASE key U.

6. Now N900 is in flashable mode. Open terminal on your computer and cd into directory you created earlier (where you saved the flashable images).

7. First you have to flash eMMC. On command line, run
sudo flasher-3.5 -F RX-51_2009SE_10.2010.13-2.VANILLA_PR_EMMC_MR0_ARM.bin -f
Replace the filename with the one you downloaded. Do not use -R with this command. That will reboot N900, and it is not recommended in official instructions to reboot between flashing eMMC and flashing Maemo. You should see on command line some messages, and finally you will notice that flashing has ended.

8. Now you will flash Maemo (kernel and rootfs). On command line, run
sudo flasher-3.5 -F RX-51_2009SE_20.2010.36-2_PR_COMBINED_MR0_ARM.bin -f -R
Replace the filename with the one you downloaded. Now flashing starts and once it is ready, your N900 will reboot itself. When it is rebooting YOU MAY DISCONNECT USB cable.

Now your phone is in “factory state”. You have Fremantle PR 1.3 in phone, but otherwise all your previous settings and extra applications are gone.