The first thing you should do is find out what kind of iPod Touch it is. To find out what type of iPod you have, you can use our ID-Your-Ipod tool.
Once you're at a step where you can see the logic board, you should use some strong isopropyl alcohol and a soft brush to remove any white-ish residue you see. Let the device dry <thoroughly> to make sure all water from the wash is gone (this will likely take a day or two in a warm, dry place if the device is opened up. Putting the iPod in a bag of rice can also be useful at this point.) When it is dry, put it back together, and you will have your best chance of it working again.