Swivel Sweeper

ok so we got a swivel sweeper....and Lowell was suppose to clean his room in order to be allowed to use it...and well...he didn't clean his room at all and so he didn't get to use it...we put the battery in and Max and I used it for a while and then I was going to use it to go clean the front room and it stopped working...and now we can't get it to work...and so Lowell is beyond upset because he can't use it at all now...we are trying to figure out what is wrong w/ the battery without much luck....:(