if your handy with a tools and have access to home depot. Grap some denatured alcohol and toothbrush(assuming you dont have an ultra sonic cleaner) . Disassemble the phone and look for signs of corrosion . More than likely you will find it on the screen or digitizer's connector or the main board. Clean with denatured alcohol with toothbrush . Brush all connectors throughly as well as the main board itself. Let it dry and reassemble and test. If problems still persist you might require main board repair or new digitizer.
- www.orlogicrepairs.com
MacBook repairs in VA