Has anyone seen this before? A friend of mine has just got an iPhone 3GS off eBay and updated it through iTunes to 5.1. However, when we looked at it in more depth, the previous owner had upgraded the modem firmware to 6.15.00. Now the update seems to have gone through OK, but a blank Cydia icon remains on the springboard. I've been scratching my head for hours and can't figure it out. Would the iTunes update not have deleted all traces of a previous JB?