I Noticed a lot of confusion here in the process of Unlocking BL -me was one of the confused- so please make sure to do/notice those points before/during unlocking procedure
THIS THREAD IS ONLY FOR CAUTIONS. actual steps are here http://forum.xda-developers.com/show....php?t=1254087
THANKS TO 9Lukas5
IF U DON'T KNOW HOW TO USE FLASHTOOL FOLLOW http://forum.xda-developers.com/showthread.php?t=928343
FOR GUIDANCE about SIM lock and which patch to use refer to 9Lukas5's thread and replies.
BUT generally use "qsd8250_semc" if ur phone came
2.unlocked by code
and use "qsd8250_setool2" if u have unlocked it with "setool"
ANYWAY u can always use the other patch if ur signal is lost after using the first.-i have less knowledge about this issue as my phone came pre-unlocked and didn't try to unlock another one-.
FIRST OF ALL
1.USB Port not broken -can't do any upgrade or unlocking with a broken one-.
2.enabled "unknown sources" from settings/applications
3.enabled "USB debugging" from settings/applications/development. -should display "USB debugging connected" in notifications bar after USB connection IF NOT: pls flash another ROM and root it using aZUZU method as UNlocking won't work for u-.
AFTER FLASHING downgrade aZUZU kernel
4.MAKE sure ur FLASHTOOL -GB ready version- recognize the phone after SE logo displays on ur phone -FLASHTOOL should say "xperia x10 connected" then shows ur busybox version.
5. IF it doesn't recognized ur phone pls...UPDATE ur SE PC COMPANION.
6.if u don't like to update PC companion..USE THIS METHOD as 9Lukas5 describes
You don't need to update pccp or seus. Try the following:
1. open the drivers manager of your pc
2. connects phone in flashmode (without running any program like flashtool, seus or pccp)
3. check if there appears an unkown device, which wasn't there before (if not go on, if yes read under the line in this post further on)
4. no unknown device? Good
5. turn on phone and connect usb cable again and check again for unknown devices
If there is an unknown device, download flashtool 0.3.0.0 (it contains the 2.3.3 adb and flash drivers)
1. In Flashmode is an unknown device: Go to flashtool 0.3.0.0 folder then to drivers and install the exe file you find there
2. After turning on there is an unknown device: extract the x10 drivers archive in the drivers subfolder of flashtool 0.3.0.0 and search manually in that folder for the drivers of the unkown device, then they should be installed.
3. Now check again like I described it above the line for unknown devices, if you can't see them now, try again to unlock your bl.
7.be sure u have disabled all antivirus services and turn off ur firewall
8.close flashtool before starting to unlock BL
9.kill all processes named adb.exe by ur task manager "ctrl+alt+delete/start task manager/processes/sort by name/then kill adb.exe"
DURING UNLOCKING PROCEDURE
10.IF messages like "killing adb server..error" appears. pls make sure again u did points 6+7+8.
11.U HAVE TO WAIT A while and phone reboots in the process
DURING FLASHING Doom kernel v4.0 or stock
12. if messages like start flashing then abort flashing -with GB ready FLASHTOOL- or sending loader then along wait after flashing kernel .sin-with older FLASHTOOL - then u haven't probably unlocked ur BL . SO PLS don't bother ur self trying to re flash the kernel and check if ur bootloader is still locked
DID U follow steps+cautions?!!
13.to CHECK the status of ur bootloader pls download s1tool from
press "DO job" then connect ur phone in flash mode -green LED light-.
14. IF ur phone is UNLOCKED then status should be like this:
Welcome to S1 identify tool
TO CONNECT NEXT PHONES
X10 Xperia,E10 Xperia Mini,E15 Xperia X8,U20 Xperia Mini Pro
LT15 Xperia ARC,MT15 Xperia NEO,R800 Xperia PLAY
PRESS AND HOLD "BACK" BUTTON...
PLEASE ATTACH TURNED OFF PHONE NOW
RUNNING S1_EROM VER "r8A033"
NOTICE THE LOWER CASE letter "r" in "RUNNING S1_EROM VER "r8A033""
14.IF it isn't unlocked u would see UPPER CASE "R" like "R8A033" then try again with more caution then refer back to the thread
AFTER COMPLETEING THE PROCEDURE
15.of course u will see "XPERIA" Logo instead of "SONY ERICSSON" what Doomkernel u chose -v04b or v04-FS-.
16. 'SE' logo stll appears in cases:
1.u still on ur old kernel.
2.u flashed Doom's stock kernel for unlocked bl.