I have an iphone 3gs whith version 4.1 and i would like to restore it whithout upgrading version but itunes gives me various errors, the firs error was solved by using tinyumbrella but now itunes gives me error 1604 and i dont krow how to solve it. i cant have the newest version because both my lock and home buttons are broken and i use activator but if i restore it i wont have activator(obviusly). the main problem is that the newest versions require both buttons to be jailbroken.
It's pretty much useless if your home and power buttons are broken. You can probably restore to a stock 4.1 firmware but you can't do a custom firmware just bc it requires pwned dfu mode. As for jailbreaking, you probably won't be able to do it anymore without those buttons as most tools require dfu mode. Jailbreakme doesn't but that only works on 4.3.3 4.3.2, 4.3.1, and 4.3 (someone correct me if I'm wrong).
As for unlocking, if you need it, you can't restore to stock firmware or you'll lose your baseband. That means you need a custom firmware, which requires pwned dfu, which of course you can't do without those buttons working.