My device doesn't react to touches while connected via USB
The problem you mentioned can be caused by the following:


Your micro USB port in the phone has some moisture.
Your micro USB port connection is loose.


If it happens normally which is not your case, it can be caused if there is moisture on your screen or droplets of water. 

Try testing if this happens while using the mobile with charger connected. If it does, it is definitely the micro USB issue.