The touch screen is no longer responding

My son dunked my wife's iPhone 4 in a cherry slurpy. Not a fun day. Once the phone was recovered from the drink and dried off, it started acting strange. It would start playing songs at random and activating voice control at random so I powered it off. It then powered itself back on and the behavior continued. All of the touch screen worked just fine, but it kept a memory or shadow of the previous screen. I decided I had no choice (at least that's how I explained it to my wife) but to open the phone and try to fix it. I opened it just fine and was able to clean it out without any problems. When I put it back together I was pleased to find that it no longer did things at random. Unfortunately the touch screen no longer works.

I thought that perhaps I missed a connection so I took it back apart and reassembled it again. Still the touch screen does not work.

Is there maybe something that I have overlooked? A spacer that has come loose or a ground that is easy to misalign? Or, is it more likely that I managed to ruin my touch screen when I took the phone apart?

Is there a way to test if the touch portion of your screen is broken? Everything else on the screen seems to be working fine.