Hello,

I have big problem with software in one iPhone. So is stuck in DFU mode after upgrading from 4.0.1 to 4.2.1. Now screen is death when i push power button and power +home for 10 seconds, 30 seconds, 1 minute I tried many combinations. When I connect it to PC than is detect in DFU mode iTunes says the same thing, screen is all the time death. I can click restore choose iOS but i had trying few like 4.2.1, 4.1, 4.0.1 and at the beginning everything is ok but at one moment iTunes trying to reconnect i hear the sound unplug and plug in then iPhone screen turn in to white and iTunes inform me about error 21. When TU is working iTunes give me error 1602. Blackra1n see device but is stuck on running and screen is all the time black.

iPhone 3g
Windows XP sp2

Please help me

Try to restore 3.1.3

Originally Posted by Olethros

Try to restore 3.1.3

everything is the same error 21 when iPhone is preparing to restore :/

Originally Posted by korni1989

everything is the same error 21 when iPhone is preparing to restore :/

Restore logs? http://www.hackint0sh.org/f137/130802.htm

iTunes version: 10.1.0.56
iPhone OS version: before 4.0.1 it was trying update to 4.2.1
Platform: OS X (here iPhone fell in DFU) and Windows
OS version: 10.5 and XP sp2
iTunes restore Log: #1412233 - Pastie

Try a different machine or this iTunes for Windows: Troubleshooting security software issues

But I have two iPhones one in good condition is working well and second wich is broken and has error 21 and first iPhone i can restore with any problems on the same machine as second has error 21 so I don`t think this is problem with iTunes version, system or machine.

Originally Posted by korni1989

But I have two iPhones one in good condition is working well and second wich is broken and has error 21 and first iPhone i can restore with any problems on the same machine as second has error 21 so I don`t think this is problem with iTunes version, system or machine.

All I know is that in my experience (and backed up by Apple's documentation) error 21 is not a hardware issue with the iPhone itself. It's a software problem.

Originally Posted by Olethros

All I know is that in my experience (and backed up by Apple's documentation) error 21 is not a hardware issue with the iPhone itself. It's a software problem.

Agreed. Every time I've had this error it's been when Apple/iTunes/my iPhone just didn't like a specific charging cable/dock cable, or a specific USB port or controller on my machine. Switching computers / cables / USB ports / controllers has *always* resolved this for me. EVEN when the same cable / port / controller / computer was capable of flashing previously. This became ESPECIALLY notable at 4.0 -- for some reason a lot of cheap dock cables would just crap out during the flashing process.

I can't, of course, state 100% that it will work for you -- but I'm definitely in agreement with Olethros about this.