So, you're a happy, long-term N900 user, and one day you buy a spare phone off eBay. It turns up, you boot it, it works, but it's running a dated, operator-specific version of the operating system and it feels completely alien. You know roughly what you should do next, you've done it before, but it's all shrouded in the mists of time.

This HOWTO does not seek to reinvent the wheel, but to provide guidelines as to what may need to be done (your setup may vary) and pointers to the relevant documentation. So far, it takes you through updating a device from an unknown software state to latest eMMC + PR1.3 and bare-metal reinstallation of an already working system using BackupMenu, as well as initial testing to verify that all the important hardware works.

Notes:

1) This HOWTO is biased towards verifying and commissioning a phone that is believed to be functional, not really towards diagnosing one that is not. Feel free to comment on other things you can/would check. It's written with semi-experienced users in mind; if you don't use or understand most of the software mentioned here, then this post probably won't serve as a beginner's guide (though I'll do my best to point you to all the relevant reading material).

Steps taken:

1) Verify that the hardware is complete, that the device boots and that the battery is charged. At this stage, I don't have a SIM card or a microSD card in the phone.

2) Reflash first the eMMC, then the latest PR1.3 according to the instructions at http://wiki.maemo.org/Updating_the_firmware. Reboot into Maemo. Set language, region and date when asked. Turn off the annoying touchscreen vibration.

3) Connect it to your local WiFi network - and find you don't have rootsh, ifconfig or apt-get at your disposal. So, use Application Manager to download and install rootsh, from Extras. If you'd like to work on the N900 from your computer, install OpenSSH Client and Server as well, but if you're intending to restore from BackupMenu then you can skip this and keep working on the device for now.

4) At some point we're going to need extras-devel for kernel-power and backupmenu, so we might as well set it up now using the instructions here. May as well go on and install kernel-power v48 while we're here, still via the Application Manager, plus the accompanying utils, and likewise BackupMenu.

5) We're approaching the point where we could use a reboot, but, we also need to test the rest of the hardware, which eventually means putting a SIM card and microSD into the new device. Let's try to do that efficiently - wouldn't it be cool to power down once, transfer the SIM and microSD, boot into BackupMenu, restore a recent backup from the SD card and test the hardware on something damn close to the current phone? To do that, let's first take the time to clone /home/user/MyDocs first, so that whatever software we restore should find what it expects when we do eventually reboot. I connected both N900s up to a Linux PC via USB cables in mass storage mode, fsck'd both FAT32 partitions, and am using rsync (on the desktop PC) to mirror one to the other; the transfer speed seems to peak at about 11MB/sec.

6) With /home/user/MyDocs synchronised between both phones, it's time to transfer over the SIM card and microSD. On the old/existing phone, we reboot into BackupMenu, take a backup of both rootfs and optfs to the SD card, and shut down. Whilst that's happening, we shut down the new phone and remove battery and back cover. Elapsed time is two hours at this point, including writing this post, and tea breaks.

7) With the backup complete and both devices shut down, transfer the SIM card and microSD to the new device. reinstall battery, boot new device with keyboard open, use BackupMenu to restore the latest rootfs and optfs backups off the SD card. Brief moment of panic at lots of tar errors about timestamps being in the future, but that'll most likely be because the preinit environment still thinks it's Jan 1st 1970, not having hwclock info.

8) Backup was restored successfully to the new device, and we reboot into Maemo. For some reason, it hasn't preserved the time and date settings I made before, but the device feels much smoother while setting the date. We boot into Maemo proper and I'm a VERY happy bunny indeed. Up comes my desktop, up comes my calendar, the phone successfully joins my network, call history is there, conversations are there, contacts are there, Angry Birds just works, with levels and progress preserved, telepathy accounts just work and my N900 SIP client is up. My overclocking settings (805MHz ideal with SmartReflex) just worked, too, which might be why setting the date was smoother. In short, BackupMenu does what it is supposed to, that's my N900 just the way I set it up, on a whole different device.

9) We will now test the remainder of the hardware, as it would be a courtesy to leave feedback for the seller promptly. We tested the USB subsystem by reflashing successfully, we tested the screen, digitiser and keyboard by using the device, we've tested the Wifi functionality, and we've tested in the crudest possible sense that the battery, CPU, RAM etc. form an apparently working device. We have yet to test anything that requires 3G connectivity.

• a call to voicemail and changing my personal greeting verifies that I can hear and be heard on a phone call
• we know the SD card slot works as we've restored a backup from it
• the Flashlight app proves both LEDs work
• the camera successfully takes pictures
• the GPS finds its satellites and
• we can play a video off the SD card proving, that the speakers and earphones work.

I don't immediately have devices to test the TV-out or the FM transmitter, but, it's becoming clear that the handset is working fine and is all but indistinguishable from the previous one, I've got my money's worth here. In fact, this seems to have worked well enough that I'm going to stick with using the new device as my primary phone, and probably take the opportunity to stick down the USB port on the old one.

More non-critical points below:

10) The one thing that didn't "just work", software wise, was that Media Player didn't find my MP3 and video files on the eMMC, and a tracker-processes -r didn't fix it. Nor did a reboot fix it and I cannot see a permissions problem or anything, so my suspect is tracker cache weirdness. I then installed tracker-cfg and used it to point trackerd explicitly to the Music directory, remove databases and reset trackerd, and this fixed it. Small price to pay, it works now.

11) A side effect of moving to new hardware is that the battery calibration is completely off. Since I just bought a new SCUD, which is almost certainly higher capacity than any of the BL-5Js I have, it's installed into the new handset and I'll calibrate it again based on that battery.

12) An unintended consequence of cloning to new hardware is that I had no idea how good my screen protector was at reducing glare and reflections, until I took the new phone out in the sun. It was barely usable and I've immediately ordered up two new screen protectors from Amazon. Something to think about for those of us actively planning to run legacy hardware...

More to follow once I've used the cloned phone for a week or two,,,

Thanks, I will use your procedure when I get my N900 back from nokia care or if not on my replacement N900 from Marktplaats.