Driving the car and it just shut off and died on me. The car wouldn't crank or start afterward. I did some research and found a common problem regarding no smart key detection, but my key is being recognized and will turn on the ignition. I hooked up my Autel Maxisys scan tool and found some DTCS in the Powertrain Control Module U0447-00 "Invalid data received from gateway A" and U0426-00 "Invalid data received from vehicle immobilizer control module". There is a TSB out for the U0447-00 code, but I do not have a battery light or any battery warnings which is the core precondition for the TSB. I do not have the Landrover SDD software, so the TSB isn't that helpful to me. I was wondering if anyone has had a similar problem. I am letting my Auxiliary Battery charge for 24 hours and hooking it back up, but when I talked to some of the service people at my local dealer they said that the battery is only related to the Eco Start Stop and isn't required for the car to crank. I will test the battery after charging and if not I will replace it. If anyone has any clue what is going on I would really appreciate the help. I might just cave in and get the Landrover SDD software, but the subscription needed for immobilizer programming which I think I need is quite expensive.