Restore EFS on Galaxy devices stuck at Samsung logo

It’s very important to backup the EFS data on your Galaxy device, but you could still have issues restoring it. Especially when you flash some custom ROM and try to restore the EFS, you could get stuck at Samsung logo when restarting your handset. At least, it’s what I have encountered.

I once tried to flash some custom ROM on my Galaxy S4 but only found that the signal is even worse. So I restored my EFS using HCKtool. Then I got stuck at the Samsung logo. Since I backed up the whole system earlier, then I tried to restore the backup using cofface’s CMW. However, there’s something wrong as it said backup failed. Later I tried to flash other ROMs I could find on various forums, but still no luck. I had no choice but to flash official ROM, do a new partition and clear the EFS data. I thought this could fix it, but to my surprise, it did not work.

I came to realize that flashing ROMs and firmware wouldn’t help as it frequently reminded me ‘fail to mount efs.’ So the most important thing is to restore it as it’s missing. I know there’s some software could restore EFS from PC, but I did not enable USB debugging.

Late that night I did some research on Google and ran to phliz’s cmw, it can restore your EFS backup from internal memory or external SD card. Here’s how:

Download and install it, then boot into recovery. Then go to Philz Settings->Custom Backup&Restore->Custom Backup Job->Backup efs. When prompt, select external SD card as it’s easier to transfer files. You can select internal storage and use ADB push command to transfer the backup file as well. Then it will generate efs.img and we need to replace it with our real EFS backup.
After the backup is done, remove the SD card from your device. Now navigate to /clockworkmod/custom_backup/.efs_backup on your PC and copy and paste your backup (efs.img).

Then again insert it into your handset and boot into recovery.  Then go to Philz Settings->Custom Backup&Restore->Restore from Custom Backups. Here only select EFS and tap start and select external SD card and it will prompt you to select your backup. It will automatically restart your phone after finish restoring. And you will see your main screen, again!

However, a new issue arose. My phone showed not registered on the network and I was not able to make calls or receive/send text messages. But I managed to download a zip called ariza_JBv02 and flashed it. Then I restarted and my handset said upgrading and I got my signal back.

So here I learned my lesson. Don’t restore EFS (always remember to backup) if you get worse /no reception after flashing any ROM, try to flash firmware or other ROMs.

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