When you purchase a device, it’s always desirable to be able to use it as you wish. Sadly, this is often not the case. This is because most of the time, people purchase devices with a carrier subsidy. What this means is that essentially the carrier is letting you purchase the device at a reduced rate, say $300 off suggested retail, with the terms of a contract stating you will stay with them for (usually) two years. This guarantees that they will keep their ARPU (average revenue per user) over that time.
The trade off is that if you break the contract, they will charge you an ETF (early-termination fee), which adds up to the same amount they “discounted” the phone for, prorated of course. Usually rolled in with that trade off is an agreement between the manufacturer and the carrier that the bootloader is locked, giving the carrier the full control of the device instead of you. Of course, with the talented developers here at XDA-Developers, bootloaders are often hacked, returning the control of the device to the user.
What often doesn’t happen though is manufacturers deciding to give you control of the device on their own, which is exactly what Sony has done with their beta flash tool they call “Emma.” Sure Samsung “leaked” ODIN, but that’s entirely different. This is Sony creating a tool and freely making it available, and then going the extra step to show you how to use it. The tool is for the Xperia S, Xperia Arc, Xperia Arc S, and Xperia T, with more devices to be added in the future. Emma is essentially a “return to stock” tool that will work regardless of what software you currently have installed on your Xperia device, though it does require the bootloader be unlocked which Sony is again more than happy to show you how to do. The other requirements for the tool are that you have Windows installed and a current version of JAVA.
You can use the tool to choose between different stock versions of firmware, which the tool will automatically download for you from Sony’s servers. There are some quirky things with the tool however, with the connection to the Sony servers being temperamental and general JAVA issues. That said, the tool is still in beta, so head on over to the discussion thread to address any issues you might be having and to download the tool.