That's enough info. Its probably the battery feed A1. I'm going to guess CFD was on the right path.
That is, the fusible link was damaged or had blown and your friend bypassed the fusable link. So for future reference when a fuse blows, find the reason.
Next will be to look for where there are signs of overheating at all of the connectors to figure out where the problem is. Also look for any wires that may be loose or that have insulation cut or rubbed off.
Here's one of the
rare examples of ammeter connections damaged - that seems to be mostly from corrosion. (Not a ralley dash)
More often people blame the ammeter when the cause is elsewhere and the pegged ammeter was ignored. A short in the alternator, a short under the dash, a wire pinched in the steeering column, a wire pinched under the hood, or running the engine to recharge a heavily discharged battery or add-ons like electric fans...