Root [Sprint/Cricket] I can't believe I deleted [System]

[jmstrat]

Can someone guide me on how I can use adb or odin just to get the "download mode" option back into my s3? Then I can just use ODIN to flash a stock s3 rom.
My phone is a sprint sph l710

 

[SprintS5guy]

what happens when you use the button combo?

 

[kwmetalfan]

Volume down+home+power doesn't work?

 

[DaisFlaque]

Here ya go... unbrick galaxy s3 - xda-developers