One RCBO killing entire board?

[Amr400]

I had a 6amp RCBO feeding a 2.5mm radial ( temporary measure)

It tripped, as I expected would

But once tripped, all the other circuits went dead?

I replaced with a 16amp RCBO, powered on, and everything back to normal?

What could have caused this?

 

[mattg4321]

Somebody without the necessary knowledge to install a consumer unit correctly.

What has that statement to do with the original question ???????

Come on it’s not rocket science to work that out!!