Booting 3GS with redsn0w. Quit recovery loop

Download redsn0w_win_0.9.6rc7b.zip

Attention: If you are on:
iOS 4.1 follow this tutorial for 4.1 3GS,
iOS 4.3.2 to follow this tutorial for 4.3.2 3GS,
iOS 4.3.3 to follow this tutorial for 4.3.3 3GS,
iOS 5 or iOS 5.0.1 to follow this tutorial for iOS 3GS quiting recovery loop,

Point to original ipsw from apple 4.2.1 (3GS): iPhone2,1_4.2.1_8C148a_Restore.ipsw

Check "Just boot tethered right now"
Just boot tethered right now iphone

Do not turn off your iphone, cause you will need to connect it to pc and boot with redsn0w.

PS:

PPS: If your downloaded file is not ipsw, but zip or other compresion format just rename it to ipsw. Do not know how to rename file on windows? Go to folder settings of explorer: TOOLS > FOLDER OPTIONS

And check the HIDE PROTECTED OPERATING SYSTEM FILES

Now you see file extension and by clicking right mouse button on file rename .zip to .ipa