Look at the tubular connector terminals in the battery to see if they're burnt, and then look at the pins on the receiver for signs of pitting. If they're burnt, the best solution is to remove the two connector blocks, unsolder the wires, then solder on a standard connector, like a deans or XT60 with an extra 3" of wire on each so that you can connect before sliding the battery on the receiver. If you never take the battery off the bike, you could solder the two pairs of wires directly without a connector. Somebody else on the forum did that mod and solved his cutting out.
You might get a temporary solution by cleaning them unless there is too much missing. Never install your battery when it's switched on. That's what causes the burning.
SYEBC were agents for that kit, which is the same as was used on their Oxygen bikes. I know that there was a batch of replacement connectors made, but I'm not sure whether there are any left. You could try contacting them.