On Saturday, 10 April 2021 at 11:40:22 UTC+1, R D S wrote:
I cycled the mains off and back on a few times by means of the RCD, now
a TV doesn't work.

could be a coincidence?
Or do folk tend to unplug stuff?

The TV might have been powered up for years and just switched to standby mode
when not in use. Many switching power supplies have a small electrolytic
bootstrap capacitor which is only ever used to help start the power supply. This
could have failed ages ago and this would only have become obvious when the
mains was switched off and on again.

John