I can confirm that it works on my Xperia go, but requires slight modifications to work on our device. First of all, you should not follow the entire procedure written by Pandemic (it results in a bootloop for the Xperia go) - use the older procedure by percy_g2 here (for reference's sake, do not use Pandemic's method of flashing the kernel - we'll be using Flashtool to do that).
As always, back your important stuff up before proceeding.
Between
9. now you are done with system files
and
10.flash it with CWM recovery
There are many additional steps required here that weren't covered, so I'll list them here.
1. You have to flash back to ICS (specifically, firmware build 6.1.1.B.1.10). Yes, really. See this guide by xfahim for the details of how to install and root it.
- Since there is currently no known way of rooting the JB firmware, we have to resort to an alternate way that goes by the name of pre-rooting. In other words, we will be flashing in a version of the firmware that has been modified to include su and the Superuser app that accompanies it. But first, we need root access, and that's something we can only do back in the ICS firmware.
2. Once installed and rooted, you will need to install a special version of CWM designed for locked bootloaders (it piggybacks on the charging subsystem). The one I linked is designed specifically for our device.
3. Copy the zip modified as per percy_g2's instructions (linked above) into the phone's internal memory. You do not need an actual SD card for this procedure.
4. Shut the phone down, then start it up again and press the volume down button repeatedly (merely holding it down does not work). You will now see the ClockworkMod recovery's menu.
5. Using the volume up and volume down buttons to navigate and the power button to confirm, go to mounts and storage, then mount /system, /data and /cache.
6. Select wipe data/factory reset.
7. Only now can you proceed on to flash the zip into the phone. Navigate to install zip from sdcard, select choose zip from sdcard and select the zip file copied into the phone.
8. Wait for the flashing process to complete (it will take about 2-5 minutes), then shut your phone down by simultaneously pressing and holding the power and volume up buttons down until three vibrations are felt. Do not allow it to restart.
9. Leave the phone off for now, then start up Flashtool and click the lightning bolt button, then OK after ensuring Flashmode is selected, then select the .ftf containing the JB firmware. Exclude (i.e. tick) the following:
- (all options in the Wipe: group)
- Exclude system
- Exclude TA
- No final verification
Everything else not specified above should be unticked (i.e. kernel, baseband, Fota, partition).
(Sidenote) Yes, I know that percy_g2's instructions are that everything except for the kernel should be ticked, but that causes the baseband to be left back on ICS (IMEI software version 22). Flashing in the other three components brings it up to version 28 again, which is the same as a stock install of the JB firmware.
10. Click OK and connect the phone when prompted to do so, then let Flashtool work on it.
11. Once flashing has completed and Flashtool clears you to disconnect the phone, do so and start it up. It is normal for some programs to fail on the first boot (I suspect it's an issue related to the dalvik cache being cleared), they will work again after a reboot.
12. Open the apps tray and look for the Superuser app. If it's present, you're successfully rooted.
