I have the following scenario :-
- Iphone 3Gs 3.1.3 ( officially locked old bootroom )
- baseband 5.12.1 - it was jailbreak but no SHSH on file ( updated to 3.1.3 via Itune from apple )
- I have manged to get 3.1.3 SHSH on file using TinyUmbrella.
I need to restore using custom IPSW but I'm always getting 1600 error.
Any suggestion ..
thanks for the support ;)