New x3 owner
 

I've just brought an 2008 facelift x3 with light front damage the car doesn't start with the key it just makes a clicking sound I've read that this could be he bst (battery safety terminal) how do I know if its gone as I've started it by jumping it for moving purposes? Any help will be much appreciated.

Diagnosis from afar: dead batt. If it is the OE batt, it's 5+ yrs old.
Easy DIY change out...

"Light damage"? Hope the new to you car works out.
GL, mD

Thanks for replying its the original battery mate, how would I know if its just a dead battery or the bst ?

I would not know...sort of don't know or recall many posts here on The Board, pointing up the BST as being a prob, esp on a fairly newer MY car.

If any of my cars or m'cycles 'clicked', I would try to resuscitate with a slow low amp overnight charge, and then buy a new batt. Batteries on these beasts are the brain power and even a low batt can instigate probs.

Buy a batt, install it, and then if you have a problem, (doubtful), come back and ask one of the mavens for help, offering more clues.
GL, mD

Battery is NG. If the BST were the issue, there would be ZERO current going to the starter.