I tried to restore from 6.1.3 to 5.0.1 on iphone 4 with valid blobs with redsn0w and after the installation, the iphone won't boot up and I get this message on redsn0w:"couldn't obtain fresh baseband blobs.It's probably no longer signed" I don't have any problems with the baseband and I've never preserved it cause I still use the iphone on a blocked carrier.