I'm not sure how it happened but it did. What are these little connectors called?

5-pin JST-XH balance connector

See: http://intofpv.com/t-tiny-jst-connectors-diagrams

You can search Amazon for 4s balance plug and a bunch will show up. Use these and you shouldn't have another issue like that. I replaced a few before I started using them and since I haven't had any problems at all.

https://bmc3d.co/products/4s-balance-plug-protectors

You can also find them on thingverse and print them yourself if you have access to a 3d printer.

https://www.amazon.com/dp/B01MCZE2HM/ref...FBb8R46QHA

And buy this while you are at it.

Iwiss XH2.0mm XH2.54mm XH3.96mm Dupont D-Sub Terminals JST Pin Crimper SN-01BM Crimping Tools for Crimper Plier for AWG 28-20 （0.08-0.5mm2） https://www.amazon.com/dp/B00YGLKBSK/ref...FBbF3CZ9ZA

On a related note, another tip for the future is that whenever you have any expired batteries that you're going to discharge and then take to the recycling centre, after you've discharged them, cut off both the XT60 (or XT30) plug and also the balance plug along with as much wire as you can and put them in your toolbox so you have some spare plugs that you can reuse in an emergency 

Thanks everyone for all the help I really appreciate it.