Will not run, or runs intermittently

I have the car listed above 4matic. The engine does not roll or crank but all the lights on the dashboard light up normally, but the fan also comes up rolling at a high speed. I have tried different things like removing the battery terminal but it is still the same. I had it scanned but the ECU could not communicate with the scanner. I saw another post just like this with a similar problem. But that would not start. Mine will randomly start for me, or have the same issue listed above. What could be the cause of my specific problem? Like a loose wire or some connection?