Snapped iPhone 3GS in half, power button got disconnected. Reconnect?

I attempted to pull out the display of my 3GS, to see if I could fix my SIM card not working, but instead I broke the plastic, and split my 3GS into 2 parts (and broke cable #3 in the process, but I don't really need it).

It's pretty straightforward to put it back together, and connecting all marked cables makes the phone boot, and the touch screen is responsive and the home button works.

However, my power button stopped working. Directly pressing on it with a finger or a screwdriver doesn't work. I then noticed a small cable coming out of it was disconnected. I have no idea where to connect it though.

Any help?