Hmmm.
I am going to send my N900 to service, and I like to send a "clean" device back to Nokia as somethimes the exchange for another unit instead of repair.

think I can manage to re-flash it by myself but
is there a way for a non-coder / non-linux to do this to not provide "My" data to others, as I do have confidential business data in it ?

any (simple) guidance will be appreciated

Not entirely sure what you mean. The flashing instructions are at http://wiki.maemo.org/Updating_the_tablet_firmware, and they don't require either Linux or coding ability to follow.

Thank you Rob1n for that link, did not have it...
BUT my question is a CONFIDENTIAL issue, what do I need to do to be pretty safe that no other "normal" person will be able to retrieve my data ?

It depends on other persons budget. If it is high enough, probably nuking your N900 with big a-bomb is enough...


e: why not overwriting your sensitive data multiple times before reflashing?

The only way to be fairly confident of erasing all data on a flash drive (so it cannot be easily recovered) is writing data to the entire drive (blocks are re-allocated on write to spread the wear, so you can't be sure that overwriting the blocks originally allocated to a file will actually affect the original data).

The simplest way to do this on the N900 is in X Terminal, using dd. The following code will create a single 1G file, containing only zeroes - repeat with different file names until the disk is full.
Alternately, you could do a similar thing by mounting it in mass storage mode and copying garbage files to the disk until it's full.