AEGs work under water guys... As I understand it, water only really causes damage if you've got complex electronics in your gun, like programmable mosfets and stuff, because in them, water causes the signals to pass through components that can't take the current without it being lowered before passing through, because the current diverts through the water instead of going through a resistor first, or whatever.
In a simple series circuit there's effectively no danger of anything bad happening whatsoever. You might blow a fuse perhaps, or burn your motor out, but I wouldn't expect that to happen because of rain, you'd have to properly dunk it under water and hold the trigger down on auto, as if forcing something to break. TL;DR you can play in the rain, your gun isn't going to break, or explode. Conversely, gas guns in my experience are terrible in the rain, obviously there's no risk of them being damaged, but if my L85 gets wet it can't hit jack shit, the hop goes all over the place and the shots come out of the barrel practically sideways, it's ridiculous.