In an Australian winter where it’s cold but above freezing, you don’t need to do anything to an EV battery to keep it stable. Below -10 and above 40 degrees, maybe.

I’d bet money that the battery was damaged removing it. They’re very heavy and the plugs can be damaged if it isn’t lined up properly. You want a hydraulic scissor lift to position and raise or lower the pack, it’s not something you can cowboy with a couple of jacks. Unless you want pack damage and a fire, I mean.

EVs are designed with a service disconnect for the high voltage pack which is what mechanics should be using. Disconnecting the 12V battery should also work, the main pack’s contactors open and disconnect it.