Iphone wont go out of DFU!!!

[chosenkill6]

I recently jailbroke and unlocked my iphone 3gs running 4.2.1 firmware. Everything was fine, i opened cydia and clicked on user and then exited and when i put in a new sim, it turned off and refuses to turn on
i tried to boot tethered but it just gives me white screen on the iphone, and when i tried to restore it gives me error code 1600
any help would be greatly appreciated
currently the iphone is in dfu and the screen is off

 

[applemike]

Press and hold the power and home buttons (for about 10 to 15 seconds) when connected to your PC or Mac until you hear the device disconnect, then start it normally.

This fixes it 99% of the time

feel free to ask for more help if this does not work for you

 

[labman]

add this info to the thread TS upgraded to 4.2.1 with the latest baseband and then used ultrasn0w and crashed it. TS did you try kicking it out with Tiny Umbrella or IREB is Itunes recognizing it. you need to get 4.2.1 reinstalled if you can. and making more threads isn't really helping you. plus MR policy doesn't like it.

https://forums.macrumors.com/threads/1085393/