Restart loop after clearing all data off 3GS

[Eagle2083]

Hey guy if you can help me out it would be much appreciated. Anyways, so I'm trying to sell my iphone 3gs and decided before I did to erase all content and settings manually from the iphone.

As the title says I'm now stuck in an eternal reboot cycle where it reboots and freezes for 10 minutes or so and then reboots and does the same thing again. I googled some other stuff and was able to put it into recovery mode (the screen where it says to plug into iTunes is recovery mode right?) and when it downloaded 3.1.3 to my computer from itunes and tried to install it gave me an error message. So now I'm back to where I was before and completely lost as to what I need to do.

Things you may or may not need to know, Its a 16GB iphone 3GS that was running 4.0.1 jailbroken. I have both a PC and a Mac I can use. Let me know if any other specs are required and thanks in advance if anyone can help me.

 

[Intell]

You can only go back to 3.1.3 if you have your SHSH blobs and your hosts file has been modded. If you don't 4.0.2 and maybe 4.0.1 (until Apple stops signing it).

 

[Eagle2083]

Alright so what all do I need to do?

 

[Intell]

Put it into DFU mode and restore to 4.0.1. If you get an error that the device is allowed for the requested build then restore it to 4.0.2. If you want to jailbreak, you'll have to mod your hosts file to point iTunes to Cydia so you can restore to 4.0.1.