this thread seems pretty dormant, well as far as my FZ40 goes once I left the battery in it (which now I usually remove and keep outside so that it wont drain) and to my surprise the battery didn't drain. this incident happened about 3months back that is about 3months after the incident first occurred.
After that I took the camera to the pool and got some great photos and videos, but once while pressing the video record button my hand was wet and through that switch water entered the camera and again it started to drain the battery, now about 2 months after the incident the camera is back to normal, so I have come to a conclusion, the upper panel where video record key, focus switch and power switch is located has to be protected from moisture at all costs. and even if water finds its way home then all we need to do is let it dry off which takes about 2months without any external aid.
FZ 40 'simple but xtream versatility' .
and now with the best smi pro...Nikon D7100 & 18-105kit