QUOTE(ken_jr @ Apr 12 2011, 07:07 AM)
iPhones on 4.2.1 i think got 3 types -
- 4.2.1 official factory unlock. therefore no need care about baseband.
- 4.2.1 carrier locked but baseband remain when upgrade from 4.1 or earlier ver.
- 4.2.1 carrier locked & update to iPad baseband 06.15.00 to unlock
step by step guide will have to be very precise .. otherwise 2nd & 3rd type of iPhones will have prob ..
last week, i update a 3GS for a friend of mine. cos he screwed up cydia when it was updated to a newer ver. cydia icon missing. he told me it's factory unlocked. so i didn't bother to check. after update from 4.1 to 4.3.1, only know it's a carrier locked set. lucky SHSH was saved in cydia. downgrade back to 4.2.1. then only can unlock & use. if SHSH not saved, i think that he walloped me already.. lesson i learnt, no matter how fren, don't do for free anymore.. & better to check the model..
As House likes to say " Everybody Lies" ....
As for step by step guide,
Go to iClarified.com and you get all sorts of tutorial. Very precise, very detailed.
As for restoring all you data. Just make sure you backup everything to iTunes before you do the jailbreak. Once the jailbreak is done, just restore the backup and sync all your apps again and all your contacts, saved data will be there.
I used PwnageTool for my 4.3.1 upgrade from a GreenPoison Jailbreak for my 4.2.1, no issue whatsoever ... I know that if you are using RedSn0w, then you will need a fresh stock upgrade to 4.3.1 and then Redsn0w will do the exploit injection to jailbreak. So two types of method and both are okay. Just depends on your preference.