How do i fix iphone 3g in dfu mode due to error 2003

Open redsnow, click extras, and select Custom iPSW. A dialog window should pop up, go to where you have the ORIGINAL iPhone 3G 4.2.1 iPSW and select it. Press ok and It should then create a NO_BB iPSW in the same location as where the original iPSW is. Second step is to enter PWNed DFU mode. Open redsnow again, click extras and select PWNed DFU mode. Follow the onscreen instructions and you should be in PWNed DFU mode. Open iTunes and a message should show stating that your device is in recovery mode. Great now press ok, hold Shift and click Restore. A dialog box should show, go towhere the NO_BB iPSW is. Click it and press ok. Your device should now be restoring. Afterwards your device should turn on.

Try plugging it into a computer and putting it into DFU mode or recovery mode. If you search how to do so on youtube there are step by step directions. If it does enter DFU or recovery mode then restore the iphone.

Are you on Windows?
This link might be helpful. There is a way to do DFU without using the power button.
http://limitededitioniphone.com/how-to-put-the-iphone-into-dfu-mode/
Thanks!

If you are getting error (1) or error (6) while downgrading the firmware, you need to put your iPhone in DFU mode before you can restore or downgrade the firmware.
Step 1. Turn off your iPhone.
Step 2. Hold down the power and home button.
Step 3. When you see the Apple logo, release the power button but continue holding the home button down.
Step 4. Open iTunes and wait for it to tell you that its in restore mode.
Alternative Method:

Step 1. Connect iphone to USB then listen to the sound when it connect and disconnect.
Step 2. Hold the home and power buttons until hear the disconnect sound then release power button.
Step 3. Wait until you hear another sound then release home button.
Alternate Method: Going Into DFU Mode Without Button Pushing: (on windows) Easier than timing the buttons just right!

1.) First download the required archive http://www.sendspace.com/file/93fx93
2.) Extract the archive to the root of your hard drive, should be C:/DFU/
3.) Connect your iPhone and ignore iTunes
4.) Goto Start - run
5.) Next type in "c:/dfu/dfu iBSS.m68ap.RELEASE.dfu"
6.) Wait for iPhone to show a "white" screen
7.) Now you may proceed to downgrade!
**also these files are found in ibrickr's directory except for the .dfu file**

I’m happy to assist further over the phone at https://www.6ya.com/expert/joe_8b8c2cd6ce148309

just switch off your phone and press home button and connect to cable and restore it from there it would get solved

DFU means Device Firmware Update. If a restore using Recovery Mode doesn't work you will want to use DFU Mode as a last resort. When placing your iPhone into DFU Mode it does not load the OS before attempting the restore


Watch the Video!
For your convenience this tutorial is available in video format also. Click the Watch It button to view the tutorial!








To put the iPhone into DFU mode so you can do an iTunes firmware restore follow these steps:

Step One
Open iTunes and connect the iPhone to your Mac.


Step Two
Press and hold the Home button and the Sleep/Wake button at the same time.


Step Three
After exactly 10 seconds release the Sleep/Wake button. Continue holding the home button until you iTunes pops up a message telling you that it has detected an iPhone in recovery mode.


The iPhone screen will remain black like this:


NOTE***: It may take a few attempts to get your iPhone into DFU mode. Generally, I hold down both buttons then release the Home button just before I think the Apple logo would appear. If you are still holding both buttons down and you see the Apple logo you are holding them down for too long!

A local apple store will be happy to restore it for you.

However you can put it into DFU mode, best looking on youtube (www.youtube.com/watch?v=fiTcKMZfyfk)

try respring it (central + power buttons together and then connect to iTunes in safe mode,choose full restore (it will erase everything but if you have back up can be restored).

confirm that your firmware is compatable with your iphone.
if you have a 2G the firmware should start with 1.1 if you have a 3G the firmware should start with 1.2
apparently unlocked or jailbroken phones with the wrong firmware will brick in this manner.
not to worry, your not the only one.
do a web search for error 1604 and you will see solutions such as this below.

• Problem: I cant restore my custom firmware. I just get error 6, 1, 2, (something low).
  Solution: This has multiple causes. Generally, you are not in DFU mode. See DFU guide. Winpwn solution after ruling out the above: Delete the device file (x12220000_4_Recovery.ipsw) in your iTunes folder. (Search for the file). This can also be caused by using the incorrect firmware image (a 3g on a 2g for example).
  ———————
• Problem: I am in DFU mode and I just get error 1604, 1602, 1601 (some 160x). I am pulling my hair out! What do I do?!
  Solution: This one sucks. There’s no single answer for it. Here are some possible suggestions:
  • Validate you are using the correct firmware. You can get this if you are using an incompatible firmware (3g for 2g for example).
  • Restart your computer and try again.
  • Try another computer
  • Try switching USB ports
  • Uninstall and reinstall iTunes 7.7

If you are not able to get out of DFU mode even after trying one of the above fixes, click here to follow the comments on BigBoss’s website.

Try restoring in DFU mode, which is different than recovery mode. I happened to stumble across it while trying to restore an iPhone 3G that a user unplugged in the middle of the 3.1 update. It kept showing an error of 1611 or 13 and wouldn't restore in recovery mode. I found this DFU mode option and the restore worked fine. The DFU mode keeps the iPhone OS from loading, so you don't run into as many compatibility problems. Go into DFU mode, then try restoring the phone and see if that works.
http://techierambles.blogspot.com/2009/09/restore-iphone-with-error-13-or-1611-in.html
To enter DFU mode:
1. Connect your iPhone to your computer
2 . Turn iPhone off. You may have to hold the power and home buttons down together to force the phone off
3. Once the phone is off, hold the power and home buttons together for 10 seconds exactly
4. After 10 seconds, release the power button but keep holding home until the computer recognizes that a USB device was plugged in
5. iTunes should detect your iPhone correctly, and also allow you to restore to the factory default settings