How to replace a bind plug?

Freechip provides the answer:

If you have old servo leads or old servo extensions you can use these, strip and twist the 2 outer wires on the 3 wire lead and short them together.

The bind plug shorts the outer 2 pins on the BATT/BND port.

If you have a helping hand you can also use small needles nose pliers you can use them to short the 2 outer pins.