[Q] Stock Samsung Galaxy S2 GT-i9100 stuck in boot - how to recover data?

Dear xda community,

I have searched wide and far through the forums but have not found the perfect solution to my problem:

I have an non-rooted Samsung Galaxy S2 (GT-I9100) stuck in boot after my stock FM radio app crashed. Boot stops in the flashing logo and won't go on from there.
Cache wipe in recovery mode doesn't help, but I do not want to factory reset without any attempt to save personal data from the internal memory.

I have tried to access my phone through adb, but cannot use the pull command to get anything off (e.g. /sdcard/, where it just tells me that 0 files have been found and 0 transferred).
Kies won't connect either.

Some forums suggest to root and flash a custom rom, but this process seems a) to involve factory reset, b) seems risky without access to anything above recovery mode, or c) seems risky because I don't know my exact kernel version to pick.

All I can get via "adb shell cat /proc/version" is this:

Linux version 3.0.31-889555 (dpi@DELL228) (gcc version 4.4.3 (GCC) ) #3 SMP PREE
MPT Thu Jan 31 14:48:54 KST 2013

I am a bit unsure whether the kernels and roms available would fit because I had to send the device in earlier last year on guarantee and got it back with a firmware jellybean update, so it's not the originial stock kernel.

I found the exact same /proc/version output in this thread (http://xdaforums.com/galaxy-s2/help/help-cf-root-galaxy-s2-tanks-t2139040) , where they recommended to use PhilZ Touch v4.22 + new XWLSD.

I am unsure if this would be a good solution for me as well even though I don't know my build number or baseband version.
Is there a way to find these out via adv? are they important? Will I brick my phone if I try to install this kernel without knowing more?

Any help very much appreciated!

(I know there's a hell lot of rooting/flashing tutorials and posts out there, but hardly any are about how to save the internal data on original unrooted phones, or how to get access to the internal memory from adb or similar on unrooted phones when they are stuck in boot. If at all possible, please give me some cues on how to fix this safely, I'm not heavy-handed with tech but have not done any rooting/flashing of phones before)

MistahBungle said:

You're overthinking this.

Best option is to flash stock firmware with Odin/in DL mode & hope that fixes the problem; it's a coin toss - half the time this will fix it on its own, half the time you'll still need to do a factory reset after flash as you'll still have bootloop. There will be no way around same despite your obvious aversion to doing a reset if just the flash doesn't fix it.

Obviously if it does work w/o reset, no data loss. Only way to find out is 'suck it & see' (I.E try it).

Click to expand...

Click to collapse

In that case, how do I pick a right firmware? Sorry if that question sounds lame, but the thing is just that I've read a gazillion warnings to pick the right kernel version or get a softbricked phone, yet I do not seem to be able to retrieve the kernel ID (the couple of characters/digits) that seem to be important for this. In other words:
is it
a) ok to just go ahead and flash e.g. any Jellly Bean Stock Rom for the GT-I9100 or the Philz Recovery Rom mentioned above (in that case, which version)?
b) or do I need to know more - and if so, how can I find out which ROM to use - with only adb working?

Thanks for the quick replies everyone, in this case I will just go ahead and try my luck.

Update: Indeed Philz Recovery worked like a charm (see link first post). I was able to get a full backup of my data with this to external SD before wiping the device. After wipe/factory reset, everthing booted normal again.

Trying to restore the data turned out to be a bit more tricky. Even though I restored only data, not system files, it returned to the previous boot problems.
In the end, I extracted the backupfile on my PC, first concatenating the *.tar.a, *.tar.b etc files using windows command prompt "copy /b XXX.tar.* XXX.tar" (replace XXX with tar archive names, e.g. "copy /b data.ext4.tar* data.ext4.tar"), then I could open and extract them with 7zip, copying the extracted backup to my external SD.
Finally, I used ES Explorer (with Root Access activated in the app settings) to cherry pick and copy my calendar and contacts (/data/data/com.android.providers.calendar/ and /data/data/com.android.providers.contacts/) and some selected app files to the phone. After a restart, I had restored these and parts of my apps, although most of their settings were gone. It seems like I missed out on where these were stored.

Anyway, I hope this will help anyone with the same problem and device to get things going again without losing their data!

Thanks again everyone here and in the other threads I read over the last days.