...jailbreak on greenpois0n.? My friend asked me to jailbreak his Iphone 4 with Greenpois0n which has been released to jailbreak Iphone 4 and 4.2.1. Everything went normal with the jailbreak but when he tried to install cydia or run it he said it was taking way too long so he turned it off and turned it on again and his iphone won't make calls or use youtube and other certain apps. All thats left are most apps.