I got this iphone used, it was already jailbroken to ois 4 and unlocked (I use T-M) but it was running slow so I downgraded to 3.1.2 and initially, everything was fine. I used cydia to unlock and used it for a few days. I was downloaded some theme in cydia and the file wasn't fully downloaded and cydia closed out and wouldn't open again. I read online that it had something to do with the update and the un-completed download. No big deal, I used iphonebrowser to delete the update files, still didn't open. Whatever, so I restored the whole phone and started from scratch and re-jailbroke it (with redsn0w 0.9.3), and tried to open cydia to unlock and it would look like it was opening and then take me back to springboard. I restored it again and re-jailbroke it with a different version of redsn0w and cydia still doesn't open. I read online to delete the "zottd" files but I looked through every file folder in the phone and I don't have any. What else is there to do? Any suggestions? Please!! This phone is completely useless without cydia and the ability to unlock! Thanks!