Worcester 28i Junior gas boiler unresponsive, no lights

I have recently moved into a property with gas. At some point today the boiler went on the fritz, with no hot water from the taps/shower and no heat from the radiators. I turned the heating on and inspected the boiler in the attic and see that there are no lights lit at all. I tried a reset as per the boiler manual instructions but did nothing.

I have been on the phone with a few service engineers and they have got me to try a few things, like turn it on and off, and to adjust the pressure. While I successfully managed to flick the on/off switch, adjusting the pressure seems to have out-foxed me. I have trepidatiously tried to turn the black dome on the top of the red tank to the left of the boiler a little either direction but this doesn't appear to do anything but either keep turning one direction, and screw off entirely the other direction (incidentally, the presence of this red tank seems to have been cause for concern with one engineer over the phone). I have included a few photos of the setup and current situation. Anyone see anything that could indicate something other than boiler death?

Thanks!

Ok, so managed to get the pressure adjusted with the key and nut on the underside. Up to over 1 in the black strip. Alas, still no heat. Likely to be a fuse or something gone.

Have you tried pushing the reset button ? there is a small triangle above the button.

I did yep. Tried pressing for 5-6 seconds like the manual said, but no luck.

Did you not ask one of the engineers you phoned to come and sort it for you?

Yes I have an engineer coming round today. I was wanting to see if it was something stupid first before I get charged a call out for something that could’ve been a simple as adjusting the pressure.

There is a reset button on the top too.