Car just died. No noise and gave gearbox issue. After researching, I ordered two new batteries as the other ones were dead. Now cranks but no start.

I have a 2016 range Rover sport diesel TD V6, L494 engine. All has been fine but after driving home the engine completely cut out as if I’ve taken the key out. There was no noise at all and we cruised to a stop. After getting towed home and leaving the car for awhile I started checking and found that both batteries were dead. The main battery had no amps to crank the car and the small battery was completely dead. After ordering two new batteries the engine cranks and turns over fine but it just won’t start. Any ideas, also am I able to upload a video showing what happens?