It is as easy as holding the alt key and hitting the restore button in iTunes to browse for 1.1.3 IPSW file. No DFU mode or anything like that!

Why I downgraded from 1.1.4 to 1.1.3 ??

Once iNdependence v 1.4b5 was released with 1.1.4 support, I went ahead and updated the iPhone (16GB 1.1.3 OTB unlocked using iJailbreak)from 1.1.2 to 1.1.4 via iTunes which gave me an error. I repeated the same and the update went fine and now I have version 1.1.4 installed on the iPhone.

I then fired iNdependence trying to jailbreak/activate my iPhone. I hit the Activate button and it didnít respond in a timely fashion showing me the Jailbreak screen. I then hit the Jailbreak tab to Jailbreak the iPhone which gave me positive results. I now proceeded by clicking on the activate button and it sorta activated the iPhone but I saw no signal. It being unlocked previously in an IPSF manner using iJailbreak, I never realized that I had to use signal.app to get a signal on 1.1.4 . I took an extreme step and hit the unlock button at this stage which promptly alerted me saying I need not unlock the iPhone if I used IPSF - I ignored it! It gave an error message saying the unlock failed.

http://windows-mobiles.com/?p=170

It was one hell of an experience, it finally came back to life from a brick though! Thank god