Would snapping the Power/Volume button cable effect the iPod?

That may sound like a vague question, but let me explain. In replacing the screen on my 4th Gen iPod Touch, I was putting everything back together, I tested it, everything worked fine, and was about to screw the metal plate back on. In the process though, I somehow nicked the Power/Volume button cable right behind the Power button (above the rear-facing camera). It was a small tear, and I thought, well not the end of the world, I guess I just won't use that button.

So I disconnected the new screen to have a better look, and didn't see any other damage. All other cables intact, everything like it should be. But when I reconnected the screen to all the ports, nothing happened. The screen didn't respond at all. I reattached the damaged screen/digitizer cables, (since it actually worked, it was just cracked), and it didn't respond either.

So I'm wondering if that one cable controls power to the unit, or dictates more than I thought, other than Volume and the Power button. If it is that important, would soldering a new cable on fix everything, or is it possible I shorted the battery or something else weird? Any help is much appreciated! Thanks!