iFixit's "Accepted Answer" by pollytintop is right on target!
Steve's original problem mirrors my recent experience with an iPhone 4S that "took a look" in a five foot deep salt water filter. It took me almost a half hour to fish it out, and by that time it had begun its "flashlight death spiral." Sad to see, sadder still when I thought about how long ago it was that I backed up those photos… All I could think to do was throw it, still glowing and un-turn-offable, into fresh water. Six hours later I dried it off and sealed it into a large jar with rice.
After six days of letting the rice work it's magic I used iFixit's "Liberation Kit" to replace my iPhone's trashed battery with one from iFixit. [Note: This option is a tad pricier than other replacement options, but over the years iFixit has proven to "give good weight" and I feel good when I am able to support their efforts to fix-and-not-trash the world around us.] After the 4S was buttoned back up (with those Philips head screws) I plugged it into a charger, just because. Six hours later I connected the iPhone to my computer and, except for the lack of ANYthing on the display, the computer treated this tortured object as if it was a normal, working iPhone. Jaw dropping concept, that, and something only surpassed by the fact that when iPhoto opened up it located my photos and allowed me to download what I had neglected to back up. That was the good news. Everything else about the 4S, with its new battery, was totally compromised and there was nothing I could do to get anything to show up on the display.
Here is where it gets marginally interesting. Figuring I now had an expensive paperweight on my hands I decided to go back in to swap the original, damaged, battery for that new iFixit battery (and swap out the Philips head screws for Apple's originals). Although these things could not pull the 4S back from the brink, this stuff might be useful if the battery on my replacement iPhone (Glyde.com) goes south. Then, just because, I reconnected the dried out phone, with it original battery, to my computer. The computer no longer recognized the 4S as anything.
Bottomline: Putting a replacement battery into a "totaled" iPhone made it act, just enough, like an object that should be able to give up something important that I wished I had properly backed up. Other than that, this exercise was a bit of a fool's errand. But if temporarily introducing a fresh battery into a dead iPhone could possibly pull back photos from the brink, it just might be worth a shot.