Update T-Mobile Samsung Galaxy S2 to Android 4.4.2 KitKat using CM 11 Nightly ROM

The official build of CyanogenMod 11 Nightlies is now available for the T-Mobile Samsung Galaxy S2. In this post you will find all the info required in order to learn how to successfully update your smartphone with the latest CM11 KitKat version.
Remember that this is not an official Samsung update, but one of the most popular custom ROMs. Installing this new ROM offers you the possibility to successfully install and test the CyanogenMod 11 Nightlies, builds that are not stable but these are based on AOSP Android 4.4.
Before starting the installation you should read the guidelines below:

• This is a guide that will work only with the Samsung Galayx S2 T-Mobile.
  - don’t use the files that you find here on any other Android smartphones.
• The T-MO Galaxy S2 that you’re about to update has to be rooted and running the latest CWM Recovery image.
  - TWRP Recovery might work with this tutorial, too.
  - note that the custom Recovery that is installed on your phone has to be updated to its latest versions, as otherwise the custom KitKat custom ROM won’t be flashed successfully.
• Factory Reset is listed in the tutorial and, it is a step that you shouldn’t skip.
  - factory reset removes all data that is stored on your phone’s system partition.
  - internal / external storage data won’t be affected by ‘factory reset’.
  > you can skip ‘factory reset’ only if your device already runs on a previous CM 11 Nightly build.
  > if you skip ‘factory reset’ and the phone doesn’t boot in normal mode, then you will need to repeat the entire tutorial once again.
• Backup data from installed apps using Helium app from Google Play Store here.
• Backup SMS text messages and APN Internet Settings using the following tools for Android: SMS backup & restore | APN Settings Backup & Restore.
• Sync all the Contacts info and People details with your default Gmail account.
  - a guide can be found here in case you don’t know how to apply this step.
• Create a NANDROID ROM Backup before starting the installation of this new CM 11 Nightly build.
  - this step is listed in the tutorial and you shouldn’t skip it, as it will set a restore point for your device, one that you can use in case the new ROM doesn’t boot in normal mode.
• enable USB Debugging from Developer Options menu.
• This guide is for advanced Android users, do not try to update your device in case you don’t know what you’re doing.
• Read the entire post, don’t skip any steps and ask for more help in comments in case you cannot complete the tutorial.
• Check the phone’s battery power charge level and make sure that it is over 5o%, so that the phone won’t switch off in the middle of the updating process.

Since you’ve read all of the above, continue to the next part of this post and learn how to successfully update your smartphone.

How to flash CM 11 Nightlies KitKat ROM for the T-Mobile Galaxy S2:

1. Download the custom ROM zip file from here.
   - make sure to download the latest build available.
2. Download Gapps for Android 4.4 ROMs from here.
3. After the download is complete, connect your smartphone with your computer and then copy both files on your device’s internal storage.
   - disconnect the phone from PC when all files are successfully copied.
4. Power off your smartphone.
5. Boot your device in CWM Recovery Mode.
   - TWRP might work too.
   - note that whatever custom Recovery you use, it should be updated to the latest available build.
6. First, create a full NANDROID ROM Backup for the installed ROM.
   - select ‘backup and restore’, then save the file on the internal / external storage.
7. Next, apply the ‘Factory Reset’ for your smartphone:
   - select ‘wipe data/ factory reset’ and confirm the process.
8. Now you can flash the new CM 11 Nightly build:
   - select ‘install zip from sdcard’, then ‘choose zip from sdcard’ and confirm the installation.
   - don’t press any buttons until the process is complete.
9. After the ROM is installed, select once again the ‘choose zip from sdcard’ and flash the Gapps zip too.
10. When both files are flashed with success, return to the main custom Recovery screen.
11. Reboot your phone now in normal mode.
    - note that the first boot process of CM 11 Nightly will take at least several minutes to complete and you shouldn’t press any buttons until the home screen appears.
12. Create / log into your CyanogenMod account and take control over your device.

Now that the installation is complete you can start testing the brand new ROM. If you cannot complete the guide then you should ask for extra help in comments.
Also, note that in case the first boot process takes more than ten minutes to load all files or in case the phone enters into a boot loop, then you will be forced to repeat the entire tutorial once again. If you do decide to repeat the tutorial, then you should make sure not to skip any steps and ask for extra help in comments.
In case you don’t like how your device works with this brand new CyanogenMod 11 Nightly ROM, then you can always choose to restore your previous ROM using the file created in step 6.