Install Android 4.1.2 Jelly Bean on Sony Xperia U ST25i using CyanogenMod 10

Xperia U ST25i to go from its current OS to Android 4.1.2 Jelly Bean? Sure thing if you read our dedicated tutorial. For this procedure we will utilize the gem called CyanogenMod. Or CM.

Don’t use another tool for this guide; or another device than the Xperia U ST25i. The many tweaks, features and not only which come with the update will help your gadget perform the best it ever had.


These are the requirements which must be considered when upgrading a device:

  • make a complete backup (you can use our tutorial);
  • your device should have its bootloader unlocked;
  • charge its battery unit;
  • turn off antivirus tools on both your comp and your phone;
  • install USB drivers for this handset on your notebook;
  • download (we used the file) and Gapps package on your laptop (via this link);
  • install a custom recovery image on your phone.Xperia-U-ST25i


  1. The Xperia U ST25i must be connected to the laptop for the first step of our guide. Then you will have to turn on mass storage on the handset and then move the Google Apps and the CyanogenMod 10 from the laptop to the SD card root of the phone without unzipping them.
  2. Next, proceed to these tasks: power the handset off, boot it into Fastboot Mode by plugging the device to your notebook and, while doing that, press and simultaneously hold Volume Up, then install a CyanogenMod 10 compatible kernel.
  3. For the latter to get flashed, you should download Fastboot Files for Sony Xperia U on your laptop. Then extract on the latter and look for adb.exe, AdbWinApi.dll, AdbWinUsbApi.dll, fastboot.exe and runme.lnk files.
  4. For the next few tasks, you will have to launch the CM10, unzip boot.img file on the laptop’s desktop and then copy the file from its original location to the Fastboot directory; the boot.img is located in the ROM’s root directory.
  5. Launch the runme.lnk file. Next, enter
    fastboot flash boot boot.img
  6. Wait for the kernel to be installed on the smartphone, then unplug the Xperia U ST25i from your PC and enter the former in Recovery Mode by doing as follows: turn the handset off, turn it back on and press Volume Up multiple times while the device is rebooting.
  7. Now make sure to create a full NANDroid backup; this is done by choosing Backup&Restore (which is in the main menu), opt for “Backup” and have patience.
  8. Then opt for Factory Reset/Wipe Data, choose Wipe Cache Partition and select the following: “Install zip from SD card” and “Choose zip from SD card”. Opt for the CM10 ROM file with “Power”. Then confirm its flashing like this: press “Yes – Install … (the file name here)“.
  9. The handset should enter Recovery Mode after the necessary file is on it. Then you will be asked to perform the following: opt for Factory Reset/Wipe Data and afterwards for Wipe Cache Partition again.
  10. [sc name=”banner-jos”]Opt for the same “Install zip from SD card” and then for the usual “Choose zip from SD card” once more. This is done so that the Google Apps is installed on your phone, too.
  11. At the end of the procedure you should confirm the flashing and then choose the Restart option. The device will then reboot. And it will have the update to Jelly Bean 4.1.2 via CM10, as we promised.

Sometimes, you will miss the old ROM that belonged to your Xperia U ST25i. So that you can get it back, you have to: enter the phone in Recovery Mode, then choose “Backup&Restore“; now opt for “Restore” and select the ROM file you wish to see back on your handset.