Just an update - great support from grainfather (company now called Bevie after rename from imake); I was dreading having to return to base but when I told them I could use a multimeter they got me to do lots of diagnostics which strangely seemed to confirmed all was well with the element, earthing etc.....
...and then we discovered it was just the led (? or bulb) on the main switch at the bottom had blown. so after the initial main board trip, it was working but just didn't look like it. Absolutely no problem with the rest of the system and it works just great without having to faff around with returns!
Double brew day for the next two days. Got to get the production line primed up again!