If it fused the plug, then you're drawing too much current for the connector to handle, or the connector is bad. It is not likely to be related to the "Actiyator"...

Possibly the contact area on the plug was a little small and possibly corroded. This would increase the resistance across the plug, causing a voltage drop during operation.

For example, If the resistance in the plug causes a 1v voltage drop at 11v at 20 Amps, you'll dissipate 20W of power just through the plug, which means it will get hot enough to melt solder. That's pretty hot ! And all directly where the two bits of metal contact!!!

You may not have such a significant voltage drop, but hopefully the above will illustrate the issue.

Consider some Deans connectors.

David