CyanogenMod releases another Custom ROM this time for T-Mobile Galaxy S2 T999. ThisĀ T-Mobile Galaxy S2 Marshmallow Custom ROM is in initial stage of development so it might have some bugs. But the further updates will make the ROM stable to use for daily basis, for now it is not advisable to use this ROM for daily basis, it's just for experiencing how the Marshmallow comes for T-Mobile Galaxy S2 T999.Samsung Galaxy S2 Skyrocket

It is necessary to have root access on your device, as you can not install custom packages directly on your device without having root permission. You should also install a custom recovery tool like CWM or TWRP/

So, now let us move forward and learn about how you can flash this ROM on your device. Make sure as this is a custom ROM it might have some bugs. So, it is advisable that you back up your data and make Nandroid back up of current ROM. But it is not advisable to flash this ROM for daily run.

Preparing your Phone

  • This instructions are only for T-Mobile Galaxy S2 T999 device do not try it on other device or you may brick your device. .
  • Device should be fully charged up to 100%.
  • Backup all the important data to some external storage.
  • USB drivers for device should be installed on the PC.
  • Make a Nandroid backup of the current ROM in case you wish to restore it.
  • Device should be rooted and its bootloader must be unlocked.
  • USB debugging mode should be enabled. Go to Settings > Developer options > USB debugging mode.USB Debugging

Install Marshmallow Custom ROM CM13 on T-Mobile Galaxy S2 T999

  1. Download Android Marshmallow based CM13 custom ROM from here.
  2. Download Android Marshmallow Google App's from here.
  3. Connect the phone to computer and transfer the ROM and Google App's file to your device internal storage.
  4. Disconnect the device and turn it off completely.
  5. Reboot the device into recovery mode, press and hold Volume Down + Power key for few seconds.
  6. When in recovery mode tap on Wipe tab and select the options you like to wipe.
  7. Now, confirm the wipe action by swiping the button on the screen.
  8. Now, return to main menu and tap on Install tab then navigate to ROM file stored in your internal storage of your device and select it.
  9. Swipe the button at the bottom to flash the ROM file on your device.
  10. In the same way flash the Google App's on your device (step 8-9).
  11. Return to main menu and tap on Reboot.

That's all you can now check the device Android version in Settings > About device > Android version.