So, I jailbroke and unlocked my 3GS on 4.2.1 to sell it (my iPhone 4 is my primary), but Ive got an issue. While trying to pre-load it with Push Doctor, the install in Cydia hung and now Cydia has no listed sources or packages listed as installed. Id like to get it back to a clean state, but Im not sure what I can do. I thought I could do a DFU-mode restore from my 4.2.1 Custom Image made by Pwnagetool, but I get an Error 1600 in iTunes when I try doing that. Trying to re-do the jailbreak with redsn0w doesnt fix Cydia. Any ideas?