I did successfully jailbreak and then unlock my 3G for 3.0 with Redsn0w and Ultrasn0w, and then I installed plenty of apps through Cydia including BossPrefs. I could not display battery percentage so decided to instali SBSettings. Without completing the SBSettings, the installation crashed. Since then, ı can not run Cydia. Every time I try, it displays the startup screen, and then crashes. Can I uninstall SBSettings without the help of Cydia ? Can I fix Cydia without completely restoring 3.0 ?
Unfortunately, you have to perform a clean install. When you are successful in jailbreaking,
1. First you have to tests iPhone apps like Mail, Safari, etc.; this process ensures that the iPhone functionalities are working.
2. Then enable wi-fi and open Cydia...this connects online to Cydia repository. If you able to connect to Cydia without crashes then the gate is open.
3. Turn off/on the phone.
4. Open Cydia and install third party application. For every installed app, make sure to perform a simple tests of the application functionality.
Most third party applications are the culprits, so beware and do a diligent testing.