[Sony Xperia P, U, Sola, Go] Barabba11:
Hi all, I installed the latest 12.1 ROM on my Xperia Go st27i, cm-12.1.MAINLINE-weekly-29-lotus.zip, I hope it's better release then

cm-12-20150125-UNOFFICIAL-lotus-Bootloop-fixed.zip which someone certified for st27i.

The only problem was that at first boot it was almost impossible to enter datas (language, google account, wi-fi,etc) cause the phone was extremely slow, need to wait 1-2 minutes for each "next screen".. probably some processes on background took all the CPU power. What can it be? Maybe it was creating thumbnails on photo contained on SD-Card? I could not expect anything alse from a new phone! Is it normal?

I would thank everyone who helped me, I wrote a detailed guide and included all necessary software to help people as me find their way easly :)

http://www82.zippyshare.com/v/fq17WMfg/file.html

Here I paste the instructions (they may help more if reported in the first post, I suppose):

0) backup all, especially contacts (use export into contacts application), move everything you need to the SD card (photos, video, movies, etc.). Be careful, the phone will be completely formatted (except SD card)

1) Go to

http://developer.sonymobile.com/unlockbootloader/unlock-yourboot-loader/

follow instructions to check if your phone is "bootable", then follow procedure inserting email and IMEI (type *06# on your phone), enable USB dubug on phone, get the code for unlock.

2) Avoid download the Android APK suggested by Sony, instead use this package:

minimal_adb_fastboot_v1.4_setup.exe included in rar, let the installer open the DOS prompt for you, and keep it open for later use. Copy on phone SD card the zip file of the ROM and the desidered open gapp (I suggest you micro edition, ARM, 5.1)

3) switch the phone off, open in your windows the device control panel, press vol+ on phone and connect usb. By the time you have violet led color you can install the driver, and here is the point: if you wait too much it will switch to red and you'll lose this chance.

Catch the new hardware and quickly target the driver to the right folder (drivers inclued in rar), repeat procedure (connect usb with vol+) until the driver has been installed, and the led keeps violet.

4) Use the already opened prompt or open a prompt on the fastboot folder, copy int this folder the file boot.img that you find into the ROM release, now paste on the command prompt:

fastboot devices to check if the phone is connected properly

fastboot -i 0x0fce oem unlock 0x <put here the code you received> ,for example "fastboot -i 0x0fce oem unlock 0x647749693EBD2D3F"

you will see an OK

now load the new bootrom, type:

fastboot flash boot boot.img

5) disconnect usb and switch on the phone, wait until you will see twrp open, go to Wipe, advanced wipe, select only data partition and click Repair or Change File System > Change File System. Now select F2FS from the list and swipe to format data partition to F2FS.

Repeat the same procedure for cache partition

Go back and now wipe the folders: system, data, cache, and Dalvik.

Go back and install the ROM zip

Go back and install the gapps.

6) wait for phone to boot, you may see it works so slowly in the beginning, be patient and complete the basic steps, let it connect to wi fi and google account. After some time you will see it working normally.

Have fun!