UPDATE (15th Sept. 2011) – A new very simple and fully working Symbian hacking method is now available for all S60 versions. Please refer to this post for the tutorial (no flashing, custom firmware, certificate or key required).
The following method also remains valid however but it is a bit complicated and risky.
After the change (on 23rd June 2011) in Dev certificate policies by Symbian Signed, you cannot easily get a device specific certificate required to sign unsigned sis/sisx files (hacking and other files) for installation. Now the only method to hack Symbian (3rd, 5th and Symbian^3) phones remains to be a tricky one – flashing the phone with a hacked firmware. In this post I will describe this method in detail (all credit goes to Marco Bellino), just follow the steps given below –
1. Download this file from here and extract the content (three .ldd files) out of the archive
2. Download Nokia Cooker from here (for Windows)
3. Download Navifirm from here (for Windows)
4. Download your original Firmware Files – Run Navifirm (internet connection required) and wait for it to load “Product list”. Search for your phone in the list and select it (for example Nokia N8, RM-596). Wait for the Navifirm to load “Releases (Software version)” in the next adjacent pane.
5. Select the latest release and wait for Navifirm to load “Variants (Product codes)”. Search and select your phones product code and wait for Navifirm to load files in the last pane. Select all the files and download them to your computer. Depending upon your phone model and internet connection speed, download may take several minutes to hours.
6. After downloading completes, run Nokia Cooker and go to File/Open or “Open Firmware” option”, locate and open the “.uda.fpsx” firmware file (one of the files you have downloaded in step 4 above).
7. In the opened file, navigate to the “bin” folder (path – sys/bin), all files in the bin folder will be shown in the adjacent pane. Now “drag and drop” (no copy/paste sorry!) the 3 .idd patch files (Step 1 above) inside the “bin” folder (in the files list at right hand side pane). After all the three files have been copied, select “Save Firmware”. Wait for a while as rebuilding process will take some time.
8. Flashing phone using Phoenix – Now follow the instructions given in this tutorial post to flash your phone with the above firmware files (including the hacked uda). Alternatively you may also use J.A.F. instead of Phoenix to flash the phone with the hacked firmware (Refer to this post).
9. After flashing is complete, download ROM Patcher+ from here and install it in the phone.
10. Now run the just installed ROM Patcher+ from menu and go to “Options/All Patches/Apply”. Exit the app and done! The phone is fully hacked now! Enjoy installing any unsigned app plus full system access (read/write in sys/private folders) via any file manager (like X-plore).