If you bricked your N9 as i did the past week, and want it back to life from the dead Nokia Logo then you can use the following method for restoring system after some dangerous experiments with applications.

My guide is based on ubuntu live cd (the best and safest method yet) as i have Win 7 64bits and i just can't run properly the tools needed to flash the N9 (if you want steps to do it on windows OS, be sure to look into maemotalk forums)...so :

In few steps :

1- Get (not really necessary) the latest ubuntu build (i did it with ubuntu 9 and it worked just fine), Once you've finished downloading your file, you'll need to create a CD or USB drive (the advantage of running a live cd is that you won't need to install anything on your PC) and then run it (see step 3 from this page).

2- Get the maemo flasher released for Harmattan (in my case i did choose the flasher_3.12.1_i386.deb version of it as i'll use ubuntu live cd) and install it !

3- Get the firmware image for your device, I used NaviFirm from http://www.symbian-toys.com/navifirm.aspx to get the appropriate firmware for my N9 (you can search your Firmware with the help of the product code of your N9 which you can find on the back of the micro SIM holder) you're not forced to download all files but ones checked by default, the most important file is the Mcu LEGACY one (something like : DFL61_HARMATTAN_2X.2011.44-2_PR_LEGACY_XXX.bin)

Ps : It'll be convenient to rename it to something easy like your name for example : saad.bin

You want to do a warm-flash ( I have not tried a cold-flash, so do that at your own risk ) of your device.

There are detailed instructions at the maemo wiki, http://wiki.maemo.org/Flasher but you won't probably need them as only what's left to you to do is to place files you've just downloaded to Desktop.

5- Place downloaded files to desktop.

6- Run Xterm, then type :

cd Desktop

Then sudo flasher -F FIRMWAREIMAGE.bin -f -R

Where  FIRMWAREIMAGE.bin is the name you gave to your firmware image... in my case the command will be :

sudo flasher -F saad.bin -f -R

Plug your N9 (it must be switched off already) and wait the magic till your device reboot ;)

It worked fine, but still, do at your own risk !

Additional type : Do a hard reset after that as you could have some old nasty files staying on the system ;)

If you have questions drop them in comments section :)