I take that to be the infamous neon screwdriver or something similar? These are highly dangerous and in any case will only show the presence of voltage...nothing to do with current.
We can never condone live testing by the public let alone rigging separate supplies to components!
Having said that, if you found the element heated when it was given a supply then it can only be a heater supply fault...being an Indesit in disguise it could be a whole number of things from the pcb down.
Power disconnected at ALL times when working on it please