4.3>4.2.1 downgrade problems

[Ashin]

Was downgrading my sisters 3GS and the following happens -

She has SHSH saved, so did the usual, installed fine, then got 1015 error, and iPhone stuck in DFU loop, tried everything... like RecBoot and TinyUmbrella recovery, what do?

 

[skillz1318]

You can always go into an apple store and say your phone won't turn on. I did that a few months ago when I was running into issues. They just plugged it into a special version of itunes they use and then restored to factory settings.

I went home and clicked restore from backup and all was good.

 

[nebo1ss]

Was downgrading my sisters 3GS and the following happens -

She has SHSH saved, so did the usual, installed fine, then got 1015 error, and iPhone stuck in DFU loop, tried everything... like RecBoot and TinyUmbrella recovery, what do?

Try the method recommended in this thread.

https://forums.macrumors.com/threads/1116875/