Reset to factory settings Galaxy S2

Moved to the International S2 root forum.

Psyckus said:

Hi everyone,

So what I did here was install Android 4.1.2 with Odin a while ago because in Mexico the S2 can't have any version after 4.0.4.

And also I installed an insecure kernel so I could have root access.

Now I want to go back to the original android OS the S2 included when I bought it and the original kernel.

I'm asking for simple manuals to leave the phone as when I bought it and the best way to backup my contact list, because I can't make the PC detect the phone anymore and I can't sync it with Kies anymore. Also the phone freezes constantly and the battery doesn't last as long as when I had Jellybean 4.0.4 (yes the battery is calibrated).

Please help.

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Hi Psyckus,
when u installed an insecure kernel ( what kernel is that exactly? ) your phone has gained root access, that's why samsung kies can't detect it anymore.
it happens with every rooted phone. no need to panic there.

if u want to put your phone in the original state, u need to download the samsung firmware ur phone came up with. and then flash it via odin.
and for that ur pc must recognize ur phone but u said ur pc can't.

so, can u tell us the model no of your phone like GT-i9100 or GT-9100G/P/M/T ?
and exactly what u installed so far including your insecure kernel and android 4.1.2 ? (can u tell us the version of these?)
and when u connect ur phone with pc , what happens? does it try to download the modem or not? (providing u r connected to internet)

Psyckus said:

Hi avushkaa, thanks for replying,

Where can I find the original firmware?

About the model number I really don't know, I'm guessing that depends on the region it's being distributed isn't it? I'll leave this screenshot to see if it might be useful to gather some info (it's in spanish, but I'm sure you can identify what is what)

Spoiler

BTW my PC does recognize the phone as a device, but I can't acces the files anymore, the only thing I can do while connected to the PC is pretty much charge it, but I'm pretty sure Odin will have no problem identifying the device.

Please let me know if you need more info, maybe I can dig more into it. Thanks I hope you can keep helping me.

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Hi,
lunatic59 already gave the answer to where you can find stock Samsung firmware.

From the picture you provided,
1. u have international version of Samsung Galaxy SII (GT - i9100).
2. u r now running stock Samsung firmware XWLSD (it's one of my favorite according to battery life in Jellybean).
3. U have rooted ur phone with siyah (it's not an insecure kernel, siyah is one of the best kernel out there).

So as to ur problem regarding battery, boot into recovery mode ( shut down the phone, then press volume up+home+power button); wipe cache , dalvic cache, fix permission ; reboot ur phone. That should fix the low battery issue. If you want to give LSD a go, do this give it 2-3 days to settle. Then decide if you want to revert back to 4.04 or not.

As for not able to access files when connected to pc, go to phone settings. There under developer option check "usb debugging". now connect to pc. Also look out for any MTP icon in the notification bar. Click it.on that page u might have to click "turn on ...". Click that, u should be able to use files when connected to pc.

If you really want to revert back to ur original stock firmware that ur phone came up with, go to SAMmobile (lunatic59 provided the link), download a 4.04 stock firmware according to ur region (it's Mexico I gather, right? ), flash that firmware via odin.
Now u r back to ur original state.

Let me know what you are going to do and how it goes.

Psyckus said:

Thanks, we'll see how it goes, I wanted to go back beacuse the phone was starting to freeze more and more often, while chatting or taking a picture or even while sleeping the phone froze while trying to sound the alarm clock

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Your phone freezes because u changed the phone's base to Ice Cream Sandwich to JellyBean.
so there might be some ICS system files remained in the phone which is causing those freezing ups when the phone tries to load from JellyBean OS.

that's why wipe cache, dalvic cache and fix permission on recovery mode.that will erase all the ICS system files ur phone has and causing those freezing ups.

that should do the trick for both freezing ups and battery life.

Psyckus said:

The battery still lasts long enough (about 20-24 hours) but before the update it could last up to 30-36 hours with the usage that I give.

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usage differs with each and every person. regardless that, XWLSD is considered to be one of the most battery friendly firmware JB has. and JB firmwares are more battery friendly than ICS firmware.

as to how long u get from ur battery, it really depends upon how u use ur phone.
when i was on XWLSD, i used to get 1-1.5 days depending upon my usage and i'm not a heavy user.
and when i was on ICS i never achieved 1 day on battery.

Psyckus said:

Thanks a lot, the phone has been working well so far and the battery lasts a bit more

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That's good news. :thumbup:
i assume u r still on JB LSD ( android 4.1.2 ).

Psyckus said:

I only cleared cache because I didn't see the clear dalvic cache and fix permission options in the recovery mode. Do you think clearing cache should do?

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Go to recovery ( vol up+home+power ).
here u can see '' clear cache parition ''
then scroll down to '' advanced '' here u will see '' clear dalvik cache '' and '' fix permission '' .
do all of these and ur phone should be running more smoothly.

Psyckus said:

On another topic do you think it would be wise to updgrade to 4.2.2?

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i can't say what's wise for u or what u should do or should not do.
i can say what i will do if 4.2.2 is released for Galaxy SII.
i will definitely upgrade my phone to 4.2.2 as it is likely to be the last update SII is going to get from Samsung.

Psyckus said:

Thanks a lot for all your help you're awesome.

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U r welcome buddy.