> The battery, I'm guessing, would've been fully drained.
Hah. Hopefully water didn't get into the battery in the first place ;)
Batteries surprisingly last a really long time as long as they are COMPLETELY drained (modern lithium has about 10-25% left after drain). Low cycling can make them last even longer in terms of decades expected, if you don't cycle the battery and keep it around 60-70%.