I just jb'd my iPhone 4 and I can't get cydia to open. Also safari won't run either. If the answer is a hard reset, that didn't work? Please remember that I'm a complete newbie at this.
If you want help provide details what firmware? What did you use to jb and version IE there are several versions of greenpos0in out. Also suggest you work on you titles a little bit. I almost didn't open this.