How to change the UIQ3 CDA using Hex Editor

Here's how to change your G900 to generic world (or any other firmware if you have the CDA code). It should be pretty easy to understand, if you have any questions pm me, but I might not reply soon (and I don't know everything too).

This also works for M600, P1i, W960, P990, and other SE UIQ3 Symbian smartphones. (not sure about older ones).

DISCLAIMER: 
If you do something wrong, it is possible that you will BRICK your G900. DO IT AT YOUR OWN RISK

Why would I want to change it?
o Firmware updates are released for the Generic World CDAs before any localized CDAs (especially eastern ones).
o You can change it to any localized firmware too, if you know the code.

Any side effects?
o No Chinese support with the Generic World CDA. You can change yours from Singapore to Hong Kong etc if you still want Chinese, but it wont make much of a difference.

What do I need?
Hardware:
o The phone, of course.
o PC with USB port, and preferably Windows XP. If you have Vista, run XS++ in XP compatibility mode to be sure. Make sure SEUS is working first!!!
o DCU 65 or DCU 60 (USB data cable). The one that comes with your phone usually is DCU 65.

Software:
o Sony Ericsson Update Service (SEUS). You probably have this on the CD that came with your phone. If not, download it.
o XS++. You can download it from here.
o HexWorkshop from here. You can use any hex editor of course, but this one is pretty good with built in checksum calculators (which will be needed).
All the software is free*. It won't cost you anything if you do it right (except time).

*HexWorkshop has a 30 day trial. More than enough to finish this.

First of all you can see your firmware versions by opening the Menu. Touch More, and touch System Information. It will give you the firmware versions. Write them down somewhere.

Steps:
1. Run SEUS.Follow the instructions. If it doesn't find new software for your phone then continue.
2. Disconnect the phone, and remove the battery.
3. Put the battery back in again.
4. Unzip XS++ in a folder (don't run it directly from the zip file, it needs a folder).
5. Run XS++
6. Tick the box called "SMARTPHONE CONNECT".

7. Turn the phone off if you turned it on again. Remove the battery and put it back again.
8. Click on the "Connect" button in XS++. It will ask you connect the phone in the same way you did in SEUS.
9. Hold down the "C" button on your phone.
10. Connect the USB cable to the phone (and the PC if you removed it, of course).
11. It will start detecting the phone and give a few messages. DO NOT RELEASE THE "C" BUTTON!
12. When its done you'll get a message "Ready for Operation". Now its safe to release the button.

NOTE: When you have the old CDA, XS++ might detect it as a W960 (I took this screenshot AFTER modding). It does not matter, its ok.

13. Don't touch anything else in XS++.
14. Click on the GDFS circle in the Configuration group.
15. You should see a button called "Backup GDFS". Click on it.
16. It will start saving the GDFS file. It will take about 30 seconds - 1 minute.
17. After its done, go to the folder where you unzipped the XS++ software. There should be another folder called "Backup" inside.
18. In the Backup folder, there will be one .BIN file with its name something like "W960_************_GDFS_BACKUP.bin".
19. Make a copy of the file, and don't touch it.

20. Install Hex Workshop if you haven't already.
21. Open Hex Workshop. Click on Options>Preferences, and under Columns, there will be a drop down box titled "Group by:". Select "2 (short)". Apply and click OK.
22. Open the BIN file in Hex Workshop.
23. You should see something like this:

Most of won't make sense, but we don't need most of it.

24. Scroll to the very end of the file.
25. Now on the right you will see the firmware versions of your phone. This is what we need to change.

26. The one at the very end is the CDA firmware. You need to change it to the Generic World 1 version. The code for the Generic World 1 is:
CDA: 1204-3148 R6J825
(The one you see in the screenshot is my old CDA firmware versions.)

27. When changing the text, you cannot select all and replace. You need to place the flashing thing before the letter you want to edit and type. It will automatically overwrite it.
28. So put the cursor before the CDA code starts and type "1204-3148" and click before 'R' and type "R6J825" (without the quotes of course). Don't type in the periods, it will change the hex code.

Left: Before
Right: After

29. So now you should have the same number of letters. Only the letters are different.
30. This is the important part. If this is not done right, it WILL NOT work.
Select exactly the same letters (on the right side) as in the picture below. Starting from the 2 dots before the first version number, to the last letter of the CDA version.

31. Click on Tools, then on "Generate Checksum".
32. Just click on "Generate"
33. On the bottom right you will see a lot of checksums and CRCs.

Note the value of the 8-bit checksum (Checksum-8, the first one). This will probably be different for you, its ok. The value will have two letters/numbers.

34. On the left side, (as in the picture) there should be a block "000D" after the selected part. In the next block, change the first two letters to the value of the 8-bit checksum. Be careful not to change anything else.

The "000D" might also appear split into two parts as shown below (thanks to medellinrob):

This is ok, it should still work.


35. Save the file under another name (but as a .bin file).

34. Connect and turn on the phone the same way as earlier using XS++.

35. Under the GDFS tab, beside the "Restore GDFS" button, select the modified .bin file.

36. Click on Restore GDFS. Might take a minute or two.

37. After its done, and XS++ disconnects the phone, take out the battery, put it back in and restart. You should now see TWO firmware versions under CDA. This is normal. But if you don't see two versions, it means you did something wrong.

38. Update the phone using SEUS, it should now detect it as Generic World 1, and will download the updated firmware. It will take a while though, depending on your internet connection.

39. After SEUS finishes everything, restart and you should see the latest firmware version and only one CDA version.

!!!IMPORTANT!!!


If it doesn't work, just restore the original GDFS, and your phone should be the same as earlier.