[Sony Ericsson Xperia Mini, Mini Pro, Xperia Pro, A] mrwitoon:
I have a rough road to update my Xperia Active. And now I've success to have my phone work smoothly. Want to share for a beginner, step by step.

1. First of all, make decision. You have to decide to leave sony. You may brick your phone. And may be, Sony cannot repair for you. If you're reluctant, I think do not do it.

2. You should have a second phone to use between the process. Or you may loss connection for a while.

3. Some word(s) you should know before ( I try to describe as simple not exactly the whole meanings, only for understand for use )

- Boot loader : is the part of Android system to load data for boot system. Sony lock this part for safety and for right issues. You should unlock bootloader before something to do. (There's some methods to root on locked bootloader but you still can't flash new rom)

- root : The way you take superuser right to change everythings in your android phone. As administrator in PC. You can check this right by use terminal emulator, write down su, the icon will change from $ -> #. If it's say " unknown command" means that you still don't rooted.

- custom ROM : There're a lot of custom roms for xperia active to choose. The most well known is CyanogeMod rom. Till now I think CM10 is stable for xperia active (It's modify from jellybean 4.1.2). There is newer version CM10.1 (JB 4.2.1) but still some bug, waiting for development. The others are Jelly Vanilla, Super jelly bean, PACMAN, Paranoid, Mike, Polish blood, etc. You can try all of them.

- flash rom : to install ROM to your device

- fastboot : the mode to flash kernel. For xperia active, connect the usb cable to your pc then power off your phone. Press Vol.up button while connect usb cable to microUSB port. You should install usb driver for xperia active into your PC. See this thread: http://xdaforums.com/showthread.php?t=1398910

- full wipe : to delete and format user data before install a new rom. You lock in to the recoverymode and then wipe data/factory reset, wipe cache partition, wipe dalvik cache (advance > wipe dalvik cache ). In mounts and storage > format system, format data, format cache.

boot in recovery mode : to restart into recovery mode, For Xperia Active you should power off your phone, then power on and wait till some boot image and LED light come then press Vol. down button repetitively for a while. If it responses, it will stop boot logo and go to recovery mode with the blue LED light.

- Kernel : boot.img. It's a boot program for your device contain some system drivers.

- recovery : It's may be as a little OS install to your device to do somethings that cannot be done via your ordinary OS. There're 2 well known brands, ClockworkMod recovery (CWM) and TeamWin Recovery Project (TWRP). For Xperia Active I suggest to use CWM.

4. Make your phone's battery > 40%.

5. Unlock Bootloader : goto http://unlockbootloader.sonymobile.com/

6. Root : go to http://xdaforums.com/showthread.php?t=1398910 .

- This will help you to find driver for xperia active (driver.zip)

- Make flash kernel easier (fastboot.zip).

- And will install Rage Kernel v3.2 (ICS) and CWM Recovery 5.0.2.7

If you like this ROM you can stop here.

7. Back up your phone. Reboot into recovery mode. Choose backup/restore > backup

8. Upgrade to Jelly Bean 4.1.2.

- Download kernel. I use 2.6.32.60 nAa kernel from: http://goo.im/devs/nAa/kernels/2.6.32/jb/satsuma (credit: http://www.androidmodmarket.com/ModMarket/Listings/XDA-L-2214282.html). It's stable, good for battery, beautiful logo. Newer kernel are good too but drain battery much faster. Rename it to boot.img and put it in your Fastboot directory (from 6) in your PC.

- Download ROM. I use Super jelly bean 5.5. It's smooth, small, little ram used, true enlargable icon(150% good for older :) ). Only problem I found is ringtone adjustment. You can go here. http://xdaforums.com/showthread.php?t=2277199

- Download Gapps. http://goo.im/gapps/gapps-jb-20121011-signed.zip

- Copy ROM, gapps into your sd card

- Flash kernel. Use flash.cmd as in 6.

- Start your phone into CWM recover and do full wipe.

- Install zip from sd card > find SJB zip file > install.

- Install zip from sd card > find Gapps zip file > install.

- After finish, restart system. Wait calmly for the first time. It may take 5 minutes.

- You can adjust your settings. And wait for 30 min. for ROM to settle. Restart and enjoy.