I turned on a light and all the lights went out in the flat. I went to reset the RCD switch but I am confused on how to do it... there is a big button labelled ON but stay in when pushed in? I turned off the second one to the left aswell and that has turned off the power to the boiler but once again I cannot push the big button in? I am used to switches so I must be doing something wrong?? Image attached in link.
https://drive.google.com/open?id=0BzWiQBeWG0oHaEJ1NFdDUlU5YUk