Guitarists: Can you help me solve this acoustic pickup problem?

So my Fishman pickup inside my Martin drains the battery oh so fast. I don’t think this is normal. I’ve literally hooked it up to amp twice with a new battery and haven’t used plug in mode for over 4 months. I plugged in the other day, and it doesn’t work at all. How is this possible?

Question: How does an external acoustic pick up work? Is it just hook the pick ups in the hole and then jack in to the amp? Can you provide a video tutorial for me? Thanks. I can’t find one at the moment.