1st Download stock RUU
2nd Try to flash the RUU 1st time (it will flash your Bootloader but will fail later becuz ur bootloader is still unlocked)
3rd relock ur bootloader (u can do this with several SXL toolkits (i prefer: http://forum.xda-developers.com/show....php?t=1865265 )
4rd ~~ now u should be able to flash the stock RUU ~~
XDA Developers was founded by developers, for developers. It is now a valuable resource for people who want to make the most of their mobile devices, from customizing the look and feel to adding new functionality. Are you a developer?