iPhone Won't Restore 1015 Error. How can I restore it?

Howdy all! A coworker of mine asked me if I could fix his iPhone, which won't restore. Since I LOVE repairing Apple anything, I said I would, but there's a problem. No matter what I do, it won't restore. It's stuck in recovery mode!

I've done tons of internet research, and as I understand it, this is a rather common problem, mostly from people who have jailbroken their iPhones.

It's great that this iPhone WAS jailbroken. lol I guess that doesn't really help me in this situation.

I suspect that's the problem, and now it's hopelessly bricked. No matter what software I download or how many ways I try to get it out of the restore mode loop, it absolutely won't boot.

Anyone got any ideas?

If I use the latest version of redsn0w, and I check Install Cydia, check Verbose Boot, Enable Multitasking, Enable Homescreen Wallpaper, Enable Battery Percentage, and Deactivate, and I let it do all of that, then if I do "Just boot tethered right now," I get the Pineapple boot logo, and the screen dims after a couple seconds. Then it just sits there forever without booting.

I'm worried the phone is practically bricked for good, or there's a legitimate hardware problem.

What do you guys think? Any ideas? I'm open to them all at this point. lol Thanks!