Carver water heater?

Hi sorry I'm knew to this..
We have a swift corvette caravan ,at the beginning of our holiday the water heater was working ok then ,we realised it wasn't turning off !!
I realised there was a dripping tap in the bathroom and and it took a while to get it stopped but by then the heater in the tank wouldn't turn off !! Now it's stopped and the red light won't go out , I'm not sure about caravans as I'm new to this can any one help ????