2014 ML350 Diesel Sudden Stop
 

Hi, guys,
I do small repairs on my ml350 but this one seems too hard for me to do alone seeking for some help.
history:
this car is 2014 has 62000 miles on it.
recently (3 months) I replace ad blue fuel pipe (pipe lost pressure leakage)
I was driving local and the car suddenly stops not slow really suddenly.
I towed it to my home.
The car won't start, no cranks no start there is a small sound when I turn the key. But very slight sound hard to describe splining maybe.
I check the battery replaced it as well as alternator I change one of there on my other car it shouldn't be the problem.
Can someone please advise me how to diagnose the problem

You need to start with a scan with an Autel grade level scanner and post codes.