RCB tripping

Thoughts please.
We had storms this week and lost all power for a three days. When power returned one of the RCB trips and would not stay on. I isolated the fault to the ducted heating.
I am perplexed, the RCB trips as soon as the ducted heating is plugged in (remains off)
I tested the socket with another device and it's not the socket,
Why would it trip when just plugged in, even the appliance is off.
Do I need an electrician or a heating technician??
I did think maybe the RCB itself is faulty!!

Thanks so much for any advice and suggestion

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It sounds Water or moisture has got into the ducted heating system electrics.

Unplug the heater and use a multimeter to check heater plug resistance between Active and Earth and report back
Ideally a Megger meter should to be used but a multimeter might be good enough.

Finding the short can be a bath plug but lets see how you go with this.

Thanks. I'll do that tomorrow in the day time , providing it stops raining!! And report back

If it trips with the heating switched off, there could also be a circuit neutral - earth.
As above, moisture where it shouldn't be..
Leave it for a few days, it could dry out and clear the fault with no attention required.

Had a look and no earth leakeage. But on closer examination I can see that the circuit board where the power supply plugs into the board is burned and scorched.
I am not sure if that is something I can fix or will it now need a new mother board ( I think that is what it's called)
I am guessing it occurred when there was a power surge during the storm event.
Any other thoughts before I call in a service technician?

Thanks all