Pretty sure it’s a PH2.0 plug. I would grab some tweezers and a small screwdriver and simply reattach the wire and insert it back into the plug.
Or if you want to run 2S, de-solder the wiring from the board and swap it for an XT30 plug (you can buy them preassembled) and run one piece 2S batteries.
[URL unfurl="true"]https://i.ebayimg.com/images/g/OS4AAOSwtnpXoadg/s-l400.jpg[/URL]
