Errors in replacing a light switch - need some help please

[terryplumb]

I have just tested the breaker for voltage and it has power into the breaker.

Do you mean there is voltage at the breakers output ?
What is the voltage at the breakers output ( top of breaker) when measured from there to earth ?
Have you correctly inserted the circuit cables live conductor into the breakers terminal. Can you show us a pic ?

 

[SUNRAY]

Going on what has been posted already, I plumped for your second option. But TBF, I have not seen inside the second hall switch

I've not seen the second switch yet either. but looking at the shape of the wires, as opposed to the position of them, I feel that circled in red looks like it's been twisted with others, much moreso than that circled yellow:

Although at this stage we don't know what has been done to the wires since removal from the original switch and OP isn't very good at answering requests & questions.

 

[securespark]

Agreed the wiring of the hall switch may still not be sussed, but the little matter of a slight lack of voltagery needs some little grey cells applying to it!

Je suis intrigué!

 

[SUNRAY]

Agreed the wiring of the hall switch may still not be sussed, but the little matter of a slight lack of voltagery needs some little grey cells applying to it!

Je suis intrigué!

At this point I'm not too sure what has been tested.

It's a nightmare, my father in law is a retired ex electrician and he came up to our house to have a look. The mainboard has power but the main live feed into the socket downstairs has no power, he is really surprised and at a bit of a loss. We cannot find any breaks in the cables and have tested everything in all sockets and lights in the ceiling and nothing, no power reaching at all.

I'd have been making other tests to at least attempt to identify cables and routes. These may of course still be ongoing.