If you are into rooting, installing custom recoveries like TWRP/CWM, and flashing custom ROMs, then whether or not you know it or not, you must, must make a backup of EFS partition of your OnePlus One. And keep it safe, always! An EFS partition backup could prove to be a big lifesaver if you ever run into trouble, when your OnePlus One gets bricked while flashing a custom ROM, or applying some memory leak fix.

Without any doubt, it’s best to create and save a EFS partition backup on your PC, so that in times on need, you can un-brick your OnePlus One easily using the EFS partition. When you lose your IMEI, you can use EFS partition to get the restore IMEI on your OnePlus One back.

How to Backup OnePlus One EFS partition

  1. Install ADB drivers.
  2. Enable USB debugging enabled OnePlus One. For this:
    1. Go to Settings > About phone, and then tap ‘Build number’ 7 times to unlock developer options.
    2. Go back to Settings, then choose now visible ‘Developer options’. Find the ‘USB debugging’ option and use its toggle button to enable it. Accept warning by tapping on OK button.
  3. Connect your OnePlus One to PC now. You will get a pop-up as shown below on your phone when you connect for the first time after enabling USB debugging. Select ‘Always allow..’ checkbox and then tap on OK button.
    Allow USB Debugging
  4. Download this one click tool. File: EFS-Backup-Restore.zip
  5. Extract the EFS-Backup-Restore.zip file to get a folder named EFS-Backup-Restore.
  6. With OnePlus One connected to PC already, run the BACKUP EFS.bat file by double-clicking on it.
  7. The tool will check for OnePlus One and when found, will run its lot of code to back up the EFS partition on your PC automatically. You won’t need to do a thing.
  8. As a confirmation, you will see two files — modemst1.bin and modemst2.bin — in the same folder where you have the Backup EFS.bat file. This is your backup, take care to save it.

How to Restore OnePlus One EFS backup

  1. With USB debugging enabled on your device as given above, connect it to PC.
  2. Go to EFS-Backup-Restore folder, and make sure you have the two files from the backup — modemst1.bin and modemst2.bin — present in that folder.
  3. Now, run the Restore EFS.bat file, and your IMEI will be restored with EFS partition in a flash.

That’s it. Let us know via comments below if you need any help with this.