Samsung Galaxy S3 boot loop backup without root

Android under construction samsung galaxy SIII case
Samsung Galaxy S3 Case Image from Zazzle

This is the story of how I managed to back up the internal storage of my unmodified non-rooted Samsung Galaxy S3 which was stuck in a boot loop. It may or may not work for other Android devices and there is no guarantee that it will work for you. However if your data is important to you, it worths a shot. No external SD card is needed for this and the phone and software wasn’t modified in any way. If you don’t care about my ramblings, jump right to the bottom for the solution in the section Riding the loop.

UPDATE: Judging by the lack of positive feedback, this method could be limited to some special cases. Either my cause for the boot loop was unique preserving a fully working system core, or developer mode and USB debugging must have been enabled before the phone broke. In either case, your mileage may vary. For future reference, here’s how to enable developer mode on Android 4.3+ before your next crash.

Something went wrong

About a week ago my android phone got into a boot loop for no apparent reason. One minute I was checking the time, in the other it was frozen with black screen and blue LED on. I took the battery out then put it back in, and off it went into a boot loop, switching between my carrier’s and the Samsung logo.

As most of the stuff I use on my phone is either an online service or synced, I wasn’t really bothered, although I wasn’t looking forward to spend an hour again to customise all the settings. Once I got over the shock of losing all my three-star levels and unlocked goodies in all Rovio games, there was one thing I really wanted to get off: my photos and videos. I’m not too keen on using a cloud service to take care of all my personal memories, and the ones on my phone were never backed up as I only used it if I had no time or I was too lazy to get a proper camera. Of course, all the data was on internal storage, as with 16GB of space, who needs an SD card?

I knew I couldn’t take the phone back to the shop, as they would have started with a full wipe and factory reset losing all my data. So what other options are there?

Download Mode

This was the first thing I found online, but despite the name, it doesn’t let you download anything. By holding down the volume down, home and power buttons, your phone boots into download mode. The only thing you can do here is to root your phone and flash custom Android images onto your device by downloading a program called Odin to your PC.

I thought I would be able to dump my phone’s full memory to a file, but the dump feature in Odin was always disabled, and I don’t actually know what it is for.

Another thing conveniently suggested on the internet is to flash custom recovery images to the phone which would allow me to create a full backup to an external SD card. First of all, I had no SD card that would have been big enough to hold all the data. Secondly, I still had no idea what was wrong with my phone, and losing the warranty by flashing stuff on it wasn’t really compelling to say the least. Better try something else…

Recovery Mode

Download mode’s little sister is the recovery mode, which gives you some limited options to troubleshoot your device without the danger of bricking it. You can boot into this mode by holding down the volume up, home and power buttons. You can try clearing the cache here, but it didn’t help in my case and was still stuck in a loop.

Another advantage is that in recovery mode, you get an ADB connection to your PC via USB. ADB is an android management tool that comes with the android developer SDK. You can look at the system log, backup files and even connect to your device’s linux shell. The downside is that in recovery mode you can’t access shit. The internal storage is not mounted in the file system and you can’t mount it without root access.

Riding the loop

While I was fiddling with my phone, I noticed that after the third or fourth boot loop iteration, it has connected to my PC via USB. As the Android system hasn’t started up, it wasn’t mounted as a USB mass storage device, but I could connect to it via ADB, the management tool from the development SDK. To my surprise, even though Android itself was rebooting over and over again, the underlying linux system worked perfectly and allowed a stable shell connection. From there I realised that the SD card was already mounted and I could access my files. Here are all the steps to copy them off:

  • Install the Android Development SDK to a folder of your choice.
  • Connect the device to the PC via USB cable and switch it on. Let it run continuously in the boot loop.
  • Start up a windows command line shell with cmd.exe
  • In the shell, navigate to the folder of the SDK tools under [SDK Folder]/platform-tools.
  • Once the phone is connected to the PC, run adb shell from the command line.
  • Within the ADB shell, find your internal storage and make sure you can see your files. For me it was under /storage/sdcard0.
  • Close the ADB shell with the exit command.
  • Make a backup folder within platform-tools (mkdir backup).
  • Copy the files off by running adb pull /storage/sdcard0 backup from the Windows shell.

Once it started copying, leave your phone in the boot loop until it finishes, for me it took about 30 minutes. As the device is hard at work, it can become quite warm, make sure it doesn’t catch fire though.

It turned out that my boot loop was caused by a software issue, once I copied my files off I did a full wipe and factory reset in recovery mode and it was working perfectly again. While connected via USB in the boot loop you can even run adb logcat to see some error messages, but for me it wasn’t much of a help, nothing obvious came up and I couldn’t have done anything about it anyway. To get a nice filtered colour-coded log, install the Eclipse Java IDE.

That’s it, I think I’ll pay more attention to backing up the files on my phone in the future. If this post helped you in any way, don’t hesitate to leave a comment below.

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14 comments on “Samsung Galaxy S3 boot loop backup without root
  1. rapskee13 says:

    same problem here. having troubles with the 5th bullet. no devices found after running adb shell. my s3 is already connected on my PC. the phone is still in the boot loop. the problem is, i cannot run adb shell because the device cannot be detected. HELP Please.

    TIA

  2. ipineda says:

    same problem, and as rapskee13, I have not been able to run adb shell because the device cannot be detected, please help

  3. zanza says:

    Hello, I’m getting the same error message; no device connected.

    Any help would be really apreciated.

    • DarthJDG says:

      Hi,

      Sorry for getting back to you so late, I was (unusual for me) asleep when you sent your message and can only address it now after work.

      Did you install the samsung s3 drivers? As I’m developing on my phone, I might have missed this step. It should be the driver pack which allows you to mount your phone as mass storage and allows USB tethering. Kies might need this driver too and should install it with it.

      You might also need to wait a few boot loop iterations without unplugging the cable for your device to be recognised. It could take one or two minutes.

      If you manage to fix it somehow, I would appreciate if you’d let me know. I have quite a few hits a day for this article, and no feedback if it actually helped anyone, your solution might help other people with the same problem. Having said that, I’m far from being an Android expert and it might well be that your boot loop is caused by a different issue than mine was.

      • Kim says:

        Hi DarthJDG,
        Thank you for assisting everyone through this issue. Your input was valuable as most responses suggest hopelessness.
        My S3 just crashed and I have been seeking a way to get my data. Mainly DejaContacts and DejaCalendar, but also would like my photos and documents.
        Anyhow, I successfully did everything up through “adb shell,” and received the “error: device not found” message. I was a programmer (DOS days) so I am not scared, just very, very outdated!
        Where do I find and how should I install the samsung S3 drivers?
        You are welcome to meet me in San Antonio:)OR simply send an email.
        I will let you know IF I have any further success.

        Thank you so much!!! Kim

  4. ema says:

    Hello DarthJDG,
    Very glad to read your posts!!
    I got the same headache on my Samsung S3!
    However, regarding the steps to copy them off via ADB, I am hesitating to do on my own due to not familiar with IT/computers at all.
    Just as a normal computer user, I want to know if those steps can be made on Windows PC (instead of Linux system)?
    Is it possible to show the steps by video (or on youtube already?) from you? That would be definitely a big help for me!!!
    Look forward to hearing from you soon.
    Thanks a lot in advance!
    ema

    • DarthJDG says:

      Hi Ema,

      Even though Android is based on Linux and all the tools are available under Linux as well, my main PC is on Windows 7, and that’s where I’ve done all the steps. I’m off to work now, but making a quick video run-through is not a bad idea actually, I’ll see if I can make one soon. I hope this method will work in your case, apart from 5 Facebook likes, I have no feedback if it worked for anyone else.

      I removed your email address from your comment, I’ll relay all messages to you via email as well.

  5. Liam Doherty says:

    Hey there Darth,

    Same issue as a number of others, whereas the 5th part, my S3 isn’t recognised by the system, I’ve tried reinstalling drivers, but that hasn’t seemed to work.

    Any help would be great, otherwise, a great article, with easy to follow instructions.

    Cheers,

    Liam

    • DarthJDG says:

      Hi Liam,

      Thanks for the feedback. It was quite a popular article for a while, I guess many people had the same issues. Unfortunately I haven’t got any positive feedback, so I can’t confirm whether it worked for anyone else than me.

      My guess is that the issue was either quite specific on the system level, or it only works if you’ve enabled developer mode BEFORE it crashed.

      The S3 is a 3-year-old model, so chances are your warranty is up anyway. I’d suggest to have a look around modding/rooting forums to see if there is a way to flash something on the device without losing the whole internal storage. That would have been my next step if I wouldn’t have accidentally stumbled upon this hack.

      Good luck!

  6. Kim says:

    I wish we had cell phone ‘jumper cables.’ At least get it started in basic mode, like task manager…

  7. Kim says:

    When I first got my S3, it showed up as a mass storage device. How can I make it do that again?
    Thanks again, Kim

    • DarthJDG says:

      Hi Kim,

      San Antonio might be a bit far away from Manchester UK, so I’ll resort to sending an email. 😉

      The reason I had to resort to the ADB shell copy method described in the article is because there was no way to mount the phone as mass storage after the crash. I’m afraid there is no way to do that unless you have a fully booting, working Android system.

      Samsung phones tend to be well supported by the Android SDK, I never had an issue with drivers, debugging always worked with the basic Windows drivers. You can try installing Samsung Kies to see if it installs a different driver, but I’m afraid the issue might be elsewhere…

      Judging by the lack of positive feedback here, the method described might only be used in special cases. There is a possibility that my crash was fairly unique, preserving a working Linux core on my phone. My other guess would be that it only works if you have previously enabled developer mode and USB debugging while your phone was still working. As I used my phone for app development as well, I have done those steps before it broke, probably that’s why the ADB shell was open.

      As this was my last resort solution, I’m afraid I can’t help you any further in this case. As your phone must be well past the warranty, you could try finding a phone modding forum on Google to see if there is a way to get root access without destroying the data on the internal storage.

      After you get your phone fixed, I suggest to enable developer mode an USB debugging, if for nothing else, it might save your data next time it breaks. Here’s how to do it on Android 4.3+:

      http://codebin.co.uk/blog/android-4-3-developer-options-missing/

      Best regards,

      Rob

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