All Radiators are cold?

Some of the upstairs radiators in my house were always cold so I bled them. This fixed the problem for that day, however, none of the radiators are now working.

When I bled them, I had to keep turning the pressure up as it kept dropping and no air was escaping until I did. The pressure is now sitting around 10 bar.

The boiler is a heatrae sadia megaflow.

What have I done and how can I undo it?

Cheers
Fraser