D4 dead flat battery - help please

[funkmiester]

Update:

Brand new earth cable with the BECM arrived today and fitted. It was a brand new cable (no kinks) but the female socket for the BECM was smashed off leaving the two pins exposed which is the same as the one I took off. I have a third one on it's way on a slow boat from Lithuania which I ordered first.....
Anyway, no joy, still can't connect to the BECM. Looking at various various diagrams it appears just to be diode?

I tried leaving the handbrake off and the car still cycles itself back on (like the list above just without the Parking brake symbol this time. The P on the gearbox lights and the pump under the bonnet runs- rinse repeat.

I checked the cables that I could find in the boot all seem tight.

Scanned, all codes gone except the BECM no contact.

So Questions:
Does anyone understand the logic of which components can "wake" the car up? At this stage it doesn't appear to be the handbrake.

This is the only code that might meant something from the first scan but it has not re-appeared
02067 - Optical data bus unauthorized awakening request Intermittent
But I can't find anything constructive on the net about it and it's currently not a live code. Car still runs perfectly, just doesn't go to sleep.