1998 320 clk suddenly died on freeway. Now won't crank or start. Electrical all working

I would take it to a better independent MB mechanic. It sounds like prior one is just throwing parts at it on a hunch. What codes are present? Does it start? What was the "F40" relay supposed to fix? Competent diagnosis is very important, otherwise you'll have a huge bill for little result......

Here's ia all the facts I know. battery is putting out 12.8 volts, key turns in ignition but does not crank. All light windows locks roof seats etc operate. We tested all fuses to be ok. When you pull starter relay and jump it turns over but no start. Could this be the esu and could it have failed out of blue while driving? OR???

also won't link to computer neither mine or mercedes unit

When you press the lock or unlock on the fob. Do the outside lights blink? Once 4 unlock 3 blinks for lock?

Randy I'm just wondering why you asked if the lights blink 4 unlock & 3 lock . Cause I have the same thing going on with my 99 clk 320 w208 . No crank no start . It was down for 2 1/2 months then one day it started . Then the 3rd day when i got home . I was going to go to the store and one click then nothing. It's been sitting for 2 weeks now. Need help BAD