The MAD approach is to 'bypass' the ammeter.
NachRT74 strategies are approaches to keep the ammeter.

There's lots of reasons why these get hot and even melt. Knowing exactly which ones got hot will help pin down the why.
The Wire from the Alternator Bat terminal goes through the bulkhead connector to the main splice. Everything comes off that main splice.
Is that the only connection that got hot?
It just might have been dirty or corroded terminal at the bulkhead.
It could be a circuit grounding out (chafed insulation) before the fuse box or circuit breaker.
Or is it the Battery wire to bulkhead that got hot?
What was the ammeter showing? That can tell a lot about what and where something is going wrong.