Updating nokia firmware
I have tested this with Symbian^3/Nokia Belle devices.
As you may know Microsoft closed down all Nokia websites (including phone software repository) earlier this year.I was also hesitant before to flash my Nokia N8 via Phoenix but now flashing my device has never been so difficult.Flashing refers to updating your device firmware(or internal Operating system) or to unlock and debrand.Flashing your phone is not an easy thing for an average mobile user.But if you can follow steps carefully then its gonna be a breeze.Your external memory (micro SD), will also be unaffected.
Flashing the e MMC and rootfs on your N900 will completely reset the device to factory settings, reverting everything to factory settings, including /home with all (app-)preferences, bookmarks, contacts, communications, but again, excluding the external memory on micro-SD card and the lockcode.
LED patterns) are reset to the original configuration, with the exception of the lock code; if you have already set a custom lock code, it will remain intact, instead of reverting to the default "12345".
Also, all information contained in which is the area visible in the default file manager (or when connecting to a computer), will remain intact.
(you MUST flash rootfs as well, when flashing e MMC (because of deletion) It is strongly advised you regularly use the Backup application to create backups of your settings and data to a safe storage.
You will want to configure the Backup application in such a way it stores the backups to your micro SD card - alternatively when creating manual backup of My Docs as suggested below, backups stored to default location "N900" will be included and thus safe.
This rendered all the firmware downloading softwares (like Navifirm, Nokia Suite, NDPM, Nokia Care Suite etc) useless.