My experience on debranding/rooting
I'm new here so I hope this thread is where it should be and it's okay to post such an experience here.
So, few days ago I bought Sony Ericsson X10i. As I understand, it was from UK's 3 Network. I bought it in Lithuania, it was already unlocked. It had R2BA020, so I rooted it, deleted some of the unnecessary apps, but... I couldn't stay calm when I knew there is newer firmware out there (I am an update maniac - all my software needs to be updated, sometimes to alpha versions). So I haven't found a guide how to update firmware here, on xda (haven't search for more than few minutes), but first result on the Google gave me the guide at xperiax10.net (I can't post the full link here as I am a new user).
I downloaded the Nordic Generic X10i Firmware (R2BA026). Started SEUS, rewritten the current firmware. Next - rename the new files to match the old files and backup the old files. So, FILE_277505303 became FILE_277466517 and FILE_277508959 became FILE_277410324.
First attempt at cheating on SEUS:
deleted the old files, successfully replaced the smaller file, but failed at the bigger file.
delete the old files, successfully replaced the smaller file, but failed at the bigger file. BUT, this time, I turned on my phone and noticed a small difference - in the locale settings, first option was United States (previously it was United Kingdom). So, third attempt:
removed only the big file, left the smaller with the old filename (FILE_277508959). SEUS started downloading the files and I see the difference in download size. It matches the Nordic Generic X10i Firmware (R2BA026). And the filenames are FILE_277505303 and FILE_277508959. Update completes, I start up the phone and what I see is new firmware! Everything works, so I download Universal Androot and root the phone.
The purpose for this post - For those who cannot debrand the phone successfully, you only need to place the smaller file in the blob_fs and then try to repair the phone twice. It worked for me, so I hope it will work for you too and make your life easier
Sorry if this post is too large