Sorry to hear about it Tom, but it is a good idea to keep batteries in it, and just maintain/swap them after charging on a regular basis.
It may sound stupid, but NO ONE plays any of my accordions unless I ask them they want to try. If I ask, it is because you have earned my respect and confidence enough that I trust you, and *I* put it on and take it off you as you stay seated.
If someone just out and out asks me, I politely refuse, I have done so many times in the past, whether I know then, or not. I've seen people in clubs come in, ask to play and do damage and more often than not, they never offer to fix what they broke and that falls to the owner to fix.
This never happened to me on the accordion, but did happen to me as a wedding photographer... I let "a friend" use a lens, and when he returned it, it no longer focused. Over $1200 to fix a $3000 lens was NOT fun for me. Never again.