Triangle Away is meant to be used immediately prior to flashing back to stock. So if the power button dies, plug it into your PC (so the screen wakes up), run Triangle Away, and then fire up Odin and flash the stock image back.
I used it when I had a T-Mobile S3 and it really does work. My Verizon S4 that I got in late August didn't come with the exploitable shipping-version of the firmware, so I haven't flashed a ROM in a long-ass time.
I do not understand what I do. For what I want to do, I do not do. But what I hate, I do.