At some point in time, you might get into your BMW N54 powered car and find that you push the start button and nothing happens. No sign of life or any clicks or anything. You might try and give it a jump start and still the same thing. There can be various reasons why this is happening but in my experience, it’s generally the following scenario that is causing your no start no crank on your n54.
On the driver side of your engine by your driver side engine mount a ground cable runs from the mount to your chassis. This cable sometimes deteriorates and doesn’t provide a good enough ground for your car and causes your no-start no-crank issue.
You can get some battery cable from a local auto parts store to use as a temporary fix. The part number to order it is “1126971302”. Usually, the reason this cable gets damaged is that your engine mounts are worn and causing the motor to move too much, or environmental factors, such as salt roads, etc.