Full autopsy completed and board up and running again.
No visible faults anywhere other than the anti spark. The buzzer was loose on the anti spark which may have created a conductive solder flake… who knows. The anti spark was compressed which added a slight bend to it which may have caused a crack in a trace… again, who knows?
Replaced the anti spark and made sure it was not squashed in the enclosure and all seems well… very nervous to push the speed now however!
I still get pain in knee and hip when I sit still for too long and have to walk…