Rads not heating

[spain]

Rads where only warm at the bottom so I bled them as I have done in the past. Seemed ok except later that night the was a very loud noise coming from the airing cupboard. It was coming from the Grundfos pump which was exceptionally hot (is that normal?).
Now all the radiators are cold and the pump still gets hot. I would very much appreciate any help or advice.
Thank you.

 

[Bahco]

Bleed the pump and release any air from the bleed screw in the airing cupboard and see if that helps

 

[spain]

How do I bleed the pump?

Thank you for your help.

 

[kevplumb]

undo the screw on the front