The problem happens when connectors that carry a decent amount of current oxidize with age. The resistance of the connection increases. And since Power (Watts) = Current^2 * Resistance, as the resistance increases, the connector gets hotter and hotter. It can be fixed, but you have to be careful. The female connector should be replaced. The male pins are soldered in to the PCB and they’re going to be hard to remove/replace without the right tools. So you’ll have to clean up the pins (which ought to look “carbonized” when you inspect). But the stuff you scrape off in order to expose bare metal is going to be conductive, you have to keep it from escaping in to other areas of the circuit board.
Personally, I’d eliminate the connector entirely and just solder the wires directly to the posts. The connector is there so it’s easier to assemble and disassemble for Formlabs. It doesn’t need a connector unless you want service from FL (they won’t service a modified machine). And soldered-on, you will have eliminated the failure mode completely. Replace the connector, over time it is likely to fail again the same way… especially since, if the posts were originally gold plated, you’ll have removed that plating leaving the posts more prone to subsequent corrosion and increased contact resistance.