The P38 diesel ECU's aren't technically OBD compliant - which is why none of their generic scanners are able to communicate with it. Only the Land Rover diagnostics - like Nanocom, Hawkeye, Testbook, and from what I gather some more specific Bosch diagnostics equipment will connect to the ECU properly.
That being said, the connector(s) behind the kick panel in the drivers footwell are known to corrode and at that connector is the link for the OBD line between the fascia where the OBD socket is and the body loom which takes it to the engine ECU. One of the wires is a Pink with Red tracer, and the other is a Light Green, again with a Red tracer.
The diesel ECU uses both of these diagnostic lines, so if one of them is corroded or broken then you won't get communication either. They then go through another connector under the coolant tank (and change colour) but the coolant tank connector is pretty well protected.
If that still proves no joy with other diagnostic systems, and it cranks but won't fire, then it does sound like a sync problem. I have syncmate units that I hire out to other owners - as they are 'plug and plug' and unfortunately I wouldn't ship my Nanocom out to someone either (I use it all the time when I'm at home for one!). I get home from work at the end of the month, so if it's not sorted by then, and are interested in a Syncmate hire for the diesel vehicle, then drop me a PM. I usually list them on eBay for buyer/seller protection but don't have any listed up at the moment as I'm away.
Marty