Using filling link on worcester 24i junior?

I need to re-pressurize my worcester 24i junior. The boiler came with the flat and I have no instructions for it.
It stopped firing up after a light bulb blew and tripped the power. The pressure isn't below 1 but it is below the red needle so I thought I should try re-pressure before calling an engineer.
The red light on the front of the boiler and will not stop if I try a reset.
The boiler has the sealed filling link. I have found the grey key required and inserted it.
Is it the white screw head to the left of the key that I need to turn to start the re-pressuring process, if so how many degrees?