Few cars react to low voltage as loudly as a Land Rover. A weak battery can light up suspension, gearbox and hill descent warnings all at once, and owners often fear a large repair when the real cause is a tired battery. Testing comes first for that reason. These cars also draw power while parked, so one that sits in a JBR basement for a couple of weeks may greet you with a low battery message.
The correct replacement is an AGM battery of the original capacity. On many start-stop models there are two: a main battery and a smaller auxiliary one that keeps the electronics steady during restarts. Both are tested, and only the weak one is replaced. The car is then told about the new battery with a diagnostic tool, which resets the monitoring system. Location varies by model, under the bonnet on some and in the boot area on others.