hello there
I had a software on my iphone 4 which made the firmware look 4.0.2 and tricks everything thinking that its running 4.0.2 when really its running 4.0.1 I cant seem to find this anywhere anymore..

I remember it had 3 buttons after installing it it was 4.0 and 4.0.1 and 4.0.2

cant remember if anyone else found this app in cydia thank you help needed

and I know you can do it manually but its easier if done with 1 click of a finger thanks