How to fix crashing and “No Service” after downgrading 06.15.00 baseband
Several of our users have been reporting issues with the 06.15.00 downgrade method we posted early this morning. Some people have been having issues getting the downgrade to go through(still trying to figure out the cause of this), but others have been successful with the downgrade but have been experiencing crashing or "No Service" errors. For those people with crashes or "No Service" try going into Cydia>Manage>Packages and select MobileSubstrate, then go to modify then click "reinstall" on the next page click "Continue Queuing" and then go back to the packages page and find Ultrasn0w and do the same for that except this time hit "Confirm." This will reinstall both Ultrasn0w and MobileSubstrate which has worked as a fix for a few different people I've talked to with these errors.