I let my grandson put a new battery in my riding mower and he reversed the cables and tried to crank it.He saidn it made some noise like it was trying to start and then it just quit.When I found the cables reversed I corrected them but it still won't do anything.No lights or anything.I thought a fuse blew but can't find one.What can my problem be?I put the charger on the battery and it said it was fully charged.