Won't Start

[kena]

Out in the X6 tonight for physio. Started at home and drove to physio without any problems. 2012 BMW E71 X6 3.0D Xdrive
Came out from physio and went to start the X6 and nothing.
Doesn't even attempt to turn over. I can hear a clicking, like a relay operating, coming from behind the area of the headlight switches in the dash.
All electrics seem OK, plenty of power.
Attempted a jump start using my wifes car and still the same.
Friend of mine who has his own body shop thinks it could be either the starter motor relay or the starter itself.
Also from research online stating it could just be the engine earth strap.
Unable to get the vehicle out of park.
It was dark and bloody freezing so locked it up and will go back tomorrow.
Any one come across this before or have any ideas what might be the problem.
I have RAC breakdown cover but honestly couldn't be bothered to call them at that time and wait half the night for recovery.
I have just come out of hospital after prostate surgery so will get it recovered in daylight to my local indy.
Thanks in advance.

[kena]

All sorted. Faulty engine earth strap. Now at my Indy getting replaced.
To test put a jump lead between the engine and the negative jumper terminal on the chassis.
RAC did this and the X6 started straight away.
I was getting a bit worried as the last thing I needed is a big repair bill before xmas

[Leslie]

That was a cheap fix , its probably shaken loose over time with the recent cold snap most struggling batteries will give up the ghost and there will be a lot of non starters soon. My battery is on the way out too need to get it sorted It's resetting the clock after a 20 mile run but it doesn't get out much these days to charge it.
Just metered my battery and its 12.1v which is a bit low .

[kena]

Apparently it's a common fault according to RAC man. They tend to corrode.
My battery was showing just over 11v before we put the jumper lead across.
I'm retired now so the vehicle tends to sit on the drive a lot nowadays.

[X5Sport]

At least it was a cheapish fix. I suppose being a copper braid then over time it will corrode away. It’s certainly common if you live anywhere near salt water. That does all sorts of nasties to pretty much any car type (except fibreglass probably).

[kena]

I live about half a mile from the coast, can see the sea out my window. I saw the old one that was removed, the culprit, it was like powder in the middle and in 2 halves. Indy said when he touched it it just crumbled.