Hi There, I have ULTRA MOTOR A2B Metro bike, when I m doing excelarte motor respond it but its not movement,.I dont know why? can you help me about it?

I had the same problem and after a while i discovered that it was overheat! inside the frame is the batery and beneath of it is the power system. i beleive that its possition is wrong! ok , it must be sealed so it can be protected from water but dont forhet that it is aircooled!!! when i opened it and tried to remove it was burning hot! that must damaged something inside there...but after a while it started again like nothing happend! i left the bottoms plastic open and i pushed it to its limits! as long as the overheat safety was on the open air ihad no problem! when i closoed it up it started not working again!