You’ve no doubt seen the UnBrickable Mod pop up on various Samsung devices in the past. For those unfamiliar, the basic premise of XDA Recognized Developer AdamOutler‘s work is to essentially make a standard consumer device function as if it were a development board. By doing this, one is able to then communicate with the system-on-a-chip directly. And because this involves talking to WORM memory, there is nothing that you could do via software to prevent this from working.
Now, thanks to Adam’s efforts, UnBrickable has been ported to the Nexus S. And just as in its other iterations, the end result is essentially the KIT-S5PC110 development board. Why is this important? Simple. Once in this mode, the “development board” essentially waits for software to run, long before firmware is loaded. This makes it possible to load literally anything onto the device, provided that it is compatible with the Hummingbird SoC and we use the appropriate custom bootloader.
In the words of the developer:
I’m not kidding when I say UnBrickable. Modifying the OM pins means you can boot from USB, UART or MMC. This makes the phone quite UNBRICKABLE. There is nothing you can do software wise to prevent the device from booting into this mode. We are communicating with the unrewritable, efused IROM on the processor. It’s the thing that makes the system on a chip into a “system on a chip”.I am here now to tell you how to turn your Nexus S into a KIT-S5PC110 development board. The KIT-S5PC110 development board is the platform used to develop our phones. There are some differences between this mod and the official development platform. The S5PC110 has a removable internal SDCard and no touchscreen.
Why would you want to do this? When you plug in the battery and connect it to the computer in “off” mode, it will become an S5PC110 board awaiting download of a program to run. This occurs long before anything like software or firmware enters the processor. This is the IROM of the device awaiting commands or a power on signal.
Because it is accepting a memory flash, anything may be put onto the device to perform a boot sequence….. Apple iOS (iPhone4 has the same processor) WP7 (mango supports this processor).
This will be a replacement for JTAG once we are able to make some firmware. I was not working with a fully operational unit when I developed this modification so I was not able to test everything… However, it did go into Fastboot and Recovery mode from a hard brick
Hardware modifications are never for the faint of heart, but those interested in giving this a shot, or at least seeing what UnBrickable is about, can get started in the modification thread.