Seems the issue is something that doesn't go back thru the firewall, so it's inside the pass compartment or maybe the trunk. Years ago I had a problem with my battery draining over night, Eventually, I found out that when I replaced the trunk lid weatherstripping it was now thick enough that the trunk light stayed on. No idea what kind of current draw that light pulled, doubt it was anywhere near what you are seeing, but pull the bulb and see.