Touch screen quit working all together

My daughters touch was getting flaky and looked like the screen was wet. (it was never in water) I sent it back to apple and they told me tuff luck it was water damaged and sent it back. I figured it was the digitizer so I purchased a new one and replaced it, checked the connections and restored it but still the screen does nothing (the water look has left) I read through the site and keep seeing that the logic board could be at fault. Is there anyway to check the board before I try to find one or could some thing else be at fault?