If you touch the metal plate next to the output jack, does the noise stop? if yes and the noise doesn't stop if you touch the strings then chances are big that the guitar cavities haven't been shielded. Or you do the job yourself if that is the case ( not diffixult with thick alu foil and some extra wires ( look it up on YT)) or you can buy a pedal called a Noise limiter and put that as first directly after the guitar.

Herman