Kistigun, one of the senior members of xda has posted the way to brand, debrand and change the firmware of Sony Ericsson Xperia Arc mobile phones. The developer has tested this method on his Xperia X10 also and it worked there too. Infact, he tested it working fine on X10 first and later confirmed working on Arc also. We are showing below the steps but please note that you should follow them at your entire risk.
Steps to Follow
1. You must have root and Root-Explorer. Basically, the requirement is that you should be able to change the build.prop file of your mobile. So, any method that allows you to do this is acceptable.
2. You should have Locked Bootloader.
3. You should have either SEUS or PC Companion.
4. Open Root-Explorer
5. Head over to system.
6. Open build.prop file with any text-editor.
7. Notice the below lines somewhere written in it:
8. You should now edit the above lines. Change xxxx-xxxx with the customization number of the firmware that you want to change to.
9. Press Menu.
10. Save the file.
11. Reboot your smartphone.
12. If you have SEUS on your pc, head over to C: –> Program Files (x86) –> Sony Ericsson –> Update Service –> db –> 13740270 and delete the folder by the name blob_fs.
13. If you have PC Companion on your computer then head over to C: –> Documents and Settings –> All Users –> Application Data –> Sony Ericsson –> Update-Engine –> db –> 13740270 and consider deleting the folder by the name blob_fs
14. Power off your mobile device.
15. For Pc Companion, use function Repair. For SEUS, use Update.
16. Reboot your smartphone.
17. You have now new firm-ware on your mobile