Grandson and his father opened the batteries, there were dry cells. Went and got the distilled water and filled them running the gen. most of the day to see if they will recover or not.
It was my fault because I haven't learned how to manage the batteries when not in use. I have a wonderful nephew that can help me with that so I don't make the same mistake.
Thank you to all of you for your help. Best people in the world on this site.