Answer to: How do I put my iPhone 3G in DFU Mode?HOLD home_button and power button for 12 secs. after 12 secs just you need to have holded into home button for 15 secs. iphone will go in dfu mode.
Answer to: iPhone 3GS stuck in dfu mode, tried almost everything?easy. just connect iphone USB to charger and it will be turned on (its important to have iphone shuted down.) next plug out usb from charger andconnect to pc next itunes will restore fimrware. if that not works use recoveryexit v3.0.