Key Not Detected, assuming short

2010 w/ 117k miles. Light comes on while car is running, not moving, in D or P, and a door closes from someone getting in/out. Have checked to ensure gate fully closed, replaced FOB battery. The 12V adapter in cig outlet is unchanged/unmoved for cell charging with same phone, only a cord was replaced. Assuming there is a short or loose wire because it happens with door closing. 12V battery is about a year old and no other electrical issues. Keys stay on flat part of accessory/storage area while driving.

Is there any way to narrow this down to FOB vs car better before hitting the dealership?