IPhone 3GS

[madmadmax]

Quick question, can I flash from 3.1.3 to 4.01 with an external program? The phone is in DFU mode.

[neodude237]

External as in what? The only external program if you wanna call it that capable of flashing firmware is iTunes.

[madmadmax]

Ok so let me re-phrase the question. I have an IPhone 3GS which is in DFU mode, iOS won't start up, ITunes gives me an error 28, ITunes does recognize the phone even the process of loading new software starts, the screen blinks and shows that it is going on and then an error message just pops up. How can I fix it?

[neodude237]

"Error 23, 28, 29, 1002, 1011, 1012, 1013, 1014, 1611: These errors may indicate a hardware issue with your device. Follow the steps in this article and also attempt to restore while connected with a known-good 30-pin Dock Connector cable, computer, and network to isolate this issue to the device. If the MAC address is missing or the IMEI is the default value (00 499901 064000 0), this can also confirm a hardware issue."
-Apple Support

[madmadmax]

"Error 23, 28, 29, 1002, 1011, 1012, 1013, 1014, 1611: These errors may indicate a hardware issue with your device. Follow the steps in this article and also attempt to restore while connected with a known-good 30-pin Dock Connector cable, computer, and network to isolate this issue to the device. If the MAC address is missing or the IMEI is the default value (00 499901 064000 0), this can also confirm a hardware issue."
-Apple Support

Correction, ITunes shows sometimes error 23 and sometimes error 13 and the phone worked just fine until it was upgraded to 3.1.3 so it's not hardware related.

[neodude237]

Try a different usb cable, different computer, usb port, etc and hope it works?

[RetiredBilly]

Try the application called "RecBoot". It has a component just to exit DFU mode.