Had the no start thing before.
Ours was caused by some NCF faults in the EEC that inhibited the start sequence. Did a full DCU download to see what faults we had, and there were lots. Common issue was a power interruption.
Removed the connectors from both EEC's applied Stabilant 22 and refitted. Everything worked fine after that.
I haven't had an engine relay box fail before. Doesn't mean they won't, just I haven't seen one fail (touch wood).
Have had 3 Eng Mode Sel panels fail. Usually engine won't go to idle from flight.
Is your machine still under warranty?