I found an iPhone4, literally in the trash. Charged it up and I could run some apps, but many things were password locked. I did see that the last time it had been used was over 2 years ago, so this is dumped, not lost.

Unfortunately, when I turned it off and rebooted (a mistake...) it just gives me a lock screen now.

So it's still locked to the original account on Apple, and no official way to use it till it's released.

Just want to reset it and use it. Needs a new battery, those are cheap and look easy to install compared to recent iPhones.
So are there any ways at all to do that?