Follow off fuse box…melted part usually lights.
I think should be 3 plugs off fuse box into engine bay..been ages since did mine could be wrong.
1 Main power from battery to starter
2 Power through harness to accessories etc
3 Engine harness
Ones with thickest earths usually plug with main power wires,most likely trace it all as common for these to melt wiring & patched up with any colour wiring or bypassed altogether.
Other trick plastic fuse cover has fuse number diagram to tell you..helps trace most of it lol.