Not sure if you know this but 72.3V is only 12.03V per battery and that means all of your batteries are at 0% State of Charge(SoC). If your battery temp sensor is failed, the zivan should still charge when you disconnect the Din plug but you won’t see the LED blinking.
But if you pull the DIN plug and your Zivan is properly wired, it should be charging. I would look at measuring the battery wires going into the Zivan( I think it’s the larger plug and there should be room for you to probe your Volt meter into the back of the connector). Obviously you should see the same voltage you see when you measure across all of your batteries.
Also, are the 2 wires connected onto the spade lugs( red and green wires)? see this trouble shooting guild and you don’t want to leave your batteries at 12.03 v for long. Lead acid batteries need to be kept fully charged when not being used or else the chemistry starts breaking down and capacity is lost forever. Troubleshooting Zivan NG1