This is a discussion on How do I downgrade 4.2.1 ios? within the iPhone Jailbreaking forums, part of the iPhone Hacking & Jailbreaking category; I wanna jailbreak my phone again,i have an iphone 4 16gb,im sick of not being able to customize it,is there any way i can down ...
I wanna jailbreak my phone again,i have an iphone 4 16gb,im sick of not being able to customize it,is there any way i can down grade it back so i can jailbreak it,i go to jailbreakme.com but says ios to new,please help,what if i do restore will that go back to my old firmwire?
You need SHSH's to downgrade. Apple doesn't like you downgrading so you have to get round it with SHSH's. Since you don't know what they are you probably won't have them.
You can jailbreak with redsnow easily but it will be tethered. Everything is explained here...