Eeeh OK ... GoPro ... what!?!?

I was just checking my stuff that I have in my messenger bag that I will bring on the plane and the small pouch with the essentials that I will have at my seat and found out that the GoPro was warm hmm how come???
So some how the GoPro had drained the battery, I use an extra battery pack on it and it was completely empty so now I am again loading it.
I will not attach the two batteries to the GoPro camera until I will use it.

Hmm I have an extra power source with me so I can load the batteries but this is not something that I had expected to happen ...