There is 230 V entering the boiler.
I can't find any dead fuses in the boiler (lots of intact ones).
Woried I've killed the PCB, surly it's not that easy to distroy?! Oh dear.
Thanks for all the help.
230v at the pcb? If so, then it’s possible that the pcb has indeed failed. Anything else carried out recently, eg a new electric meter, or anything else?
Can you post photos of the front of said boiler/ashp?
In the end the electrictian found a fuse burried somewhere deep in the heat exchanger PCB that I didn't find, replaced it and hey presto fixed in 5 minutes flat (they also then wired up the thermostat for me).