Killer-We run 9-12 over the wind in buggy all the time with the V2's.
Cheekeon-Did the lil soldered fuse blow?If you dont know where this is look right behind the negative post and look in the book to see what it's there for.
Tekin is the only company that has this and if someone hooks up batteries backwards then it will just pop the fuse sometimes.
Check that.
IF that doesnt work then simply call Tekin and ask for a RMA.
You didnt get a Lemon really just it's electronic and things happen sometimes.
Try the fuse 1st and then call Tekin if that isnt it.Their customer service is A+.
Hope this helps.
Les