I’m surprised Jaguar didn’t put a jump start terminal in the engine compartment. The easiest, safest approach I can think of is to get a battery charger that operates through the accessory/cigar lighter port and get some juice into it that way.
If the battery isn’t ruined, you can build up enough charge to pop the hatch. Such a charger might supply enough current to power the hatch release outright.
Another way is to find a large positive lead somewhere in harness, such as leading into a fuse box, and then connect a charger there (using some suitable point as the ground for the charger negative.)
Or hire a locksmith to pick the hatch lock, if there’s no way to get into the hatch to pull the emergency escape handle (found at least in U.S. market cars anyway.) From what I recall the X150 boot is sealed by a bulkhead from the rear seats.
But how are you going to do anything with the car without a physical key?