KR81

Ok, to cut a long story short, I recently found that my ecm had been damaged due to a suspected short circuit when with the previous owner. I've chased random issues for years leading up to this discovery. I've been able to have my ecm repaired here in Australia and in the process of having the damaged wires in the pics fixed along with new connectors.
What I need to know before connecting the rebuilt ecm is what could've possibly (hard to pin point I know) caused the initial short circuit? When I bought the car there was no ground strap from right side head to firewall, could this have caused it ? Any info appreciated.
Also included is a brief report from the place that has fixed it.
(Sorry, should've posted in electrical section)

Aaron R.

You need to trace the melted wires to their component to see what's up, OR use a wiring diagram to figure out what components are connected to those melted wire(s).