Hi guys. Ralekdev, Rebellos and Myself have become quite good at hacking the extra roxor out of Samsung devices. We started with The
UnBrickable Mod which now spans 15 total devices on the Samsung Galaxy S series. The UnBrickable Mod turned the Galaxy S into a development board. So we moved on to sucessfuly hacking the Qualcomm bootloaders on the
Verizon Galaxy S3 and while our exploits for this device have not yet been needed, we have them ready to deploy on several devices and we've learned alot. Today we would like to present to you:
UnBrickable SD-The ultimate in Exynos Necromancy
The UnBrickable SD allows for total resurrection of an otherwise hard-bricked and dead device. It takes a device-specific SDCard, and a jumper to be placed across a tiny resistor. This triggers the device to silently boot at which point it will count to 10 and reload the device's bootloaders. This uses Samsung Official firmware unlike UnBrickable SD Mod (unreleased as of the time of this post) which allows for dual-booting of custom and official.
Why would I need this?
The processor has a small bit of ROM called IROM that tries to initialize the EMMC to load SBOOT. SBOOT then fully initializes the EMMC(Internal and soldered down MMC chip) where it pulls boot parameters, partition tables and all other information for the device to boot. if the SBOOT is damaged, the device will no longer boot and Odin/Factory modes are destroyed and the device is hard-bricked. This failed boot means the device cannot function and is locked up.
How does UnBrickable SD work?
The UnBrickable SD works because the processor is configured to attempt to load SBOOT from EMMC and then fail-over to SD, and finally UART. We've prepared an SDCard via the sdcard command in SBOOT below. By disabling the EMMC during the IROM sequence, this device will automatically fail-over to SDCard boot, check the signatures, see a valid image, and reload the SBOOT onto the EMMC thus enabling Odin.
Instructions
You will need:
Once you have the required tools, we can begin the procedure.
- Create your UnBrickable SD.
- Unzip the SDCard Image file from the zip.
- Write it to an SDCard
- Linux:
Code:
sudo dd if=GCAM-bootable-odin-from-sd-60mb-DDimg.img of=/dev/MYDEVICE
where MYDEVICE is the sdcard (usually SDB or SDC
- Windows: use this tool https://launchpad.net/win32-image-writer/ . I'm not going to explain because I use Linux.
- Disassemble the device
I've prepared this video which shows how to disassemble the device. You can stop after you remove the LCD. Just pull the EM shields off after that so you can access the resistor.
- Insert the SDCard
If you need instructions, you should have stopped long ago 
- Short the EMMC Resistor
You can use a pair of tweezers or a piece of wire, really anything to conduct electricity from one side of the resistor to the other. Below you can see some needles connected by a piece of wire which I use to short this resistor.
- Press the power button wait a couple of seconds and release the short
While booting, the device provides a 10 second countdown on the UART2 port. during this 10 second countdown, the EMMC needs to become enabled in order to write the bootloaders back to the device. The entire process takes 30 seconds and you will see nothing on the screen.
- Flash with Odin
This procedure is the same as shown in the video below, however you will put the firmware from above in the PDA section instead of CF-AutoRoot and put the PIT from above into the PIT section
Conclusion
You have sucessfully restored your device to stock condition. Please hit the thanks button below this post.
Additional Resources
[R&D] Port SDCard Recovery to Other Exynos4412 Devices:
http://xdaforums.com/showthread.php?t=1986887
Would you like to see the UnBrickable SD on your Exynos4 device (GS2, GNote, Gnote2)? I need a working device and a broken device to develop and test.
