So, I got this phone on my trip to the US. It's a Galaxy SII variant called the S959G. It's not a very common variant, and of course it was locked to a network that's unavailable here, and comes with Android 2.3 which is ancient, so it needed some fixing.
And man, the Android community is a mess about documenting stuff. So here's my shot at it.
This only applies to THIS PHONE if you go blind doing this, or your dog catches fire, not my problem.
Done using Ubuntu (because I prefer it)
The process is a bit lengthy, but simple.
- Install heimdall
It's in the repos, just use apt, piece of cake
Go to the XDA page for this phone because that seems to be the canonical information source.
Get (from where it says "The best way to root") the CWM RECOVERY v6.0.27 file. It's called CWM-Recovery.tar.md5 because version names are for the weak.
Get the recovery.bin that's inside it using
tar xvf CWM-Recovery.tar.md5
Put your phone into download mode. For this model that's done like this:
Plug into USB
Press Volume Up and Volume Down (keep pressed)
Press power (keep pressed)
When Samsung appears on screen, let go of power button
When you see a warning sign, let go of volume buttons
Click Volume Up
Flash the recovery.bin using heimdall:
heimdall flash --recovery recovery.bin
Now you have to go into recovery to make backups:
Press Volume up and down and hold
Let go of power when Samsung flashes
There you are
In this mode, volume up/down move the cursor up/down and the power button chooses the selected option. Do the obvious thing to do a backup.
Turn on the phone and make sure it works.
Now copy the CyanogenMod zip file from XDA (or any i777 image) into the phone's SD Card somehow (drag and drop in Nautilus works ;-)
Go back into recovery mode as above.
Clean up the phone: Clean data, cache, and in advanced, clean dalvik cache.
Install by using "Install zip from sdcard" and choosing the right one, and doing the obvious thing.
Boot the phone, it should now be in CyanogenMod (yay).
Try to make a phone call. If you can't and/or the phone asks for a SIM PIN, it's still locked. To unlock I used this APK which was untested on this model, but hey, it worked.
You may also need to install one of the "modem" files from XDA. Just put them in the SD card, go to recovery, and install one, try, if it doesn't work then try another one.
Get gapps-jb-20130301-signed.zip from the XDA page.
Copy that into the SD card, then install from recovery mode.
And that's it. If it fails, you can probably go back to something reasonable using the stock firmware that's in the same page, but I have not done it so I don't offer intructions.