Quick update:
Found two resistors on ECu board burned out - the blue smoke that makes all electronics work had escaped.
It's with Gary at TD5Alive, so he can look at the codes and, if necessary, clone it
There's an inherent design flaw (LR - surprise surprise) that means sometimes, the tracks on the PCB in the ECU might be handling 80 volts at 8 amps. What Richard-head thought that might be a good idea?
So, even if I found out why, and have to spend £500+ to replace it - all I have is a brand new, but badly designed piece of kit that I hope might last another ten years
Will update when I've found more about why such a vulnerable piece of overpriced kit should be so easily compromised within the normal operating conditions.