Only thing that "works" is the instrument cluster. Car is dead to everything else. There is a noise that does not stop in the engine compartment. This is what it sounds like.

https://youtube.com/shorts/1fY3R5y2SH0?si=wTzBSjVdeghXsiPA

Ive replaced starting and Aux battery. I've checked all 3 fuse blocks. I've checked the can bus connectors. I've pulled fuses 1 by 1 to try to get the ECU to come alive. Can someone tell me which relay ia for the starter?

My expensive scanner can only communicate to the ignition lock and steering column. Everything else is no can bus communication

 

I have a 2011 Mercedes GLK350 that sat for about 4 weeks. During the time it sat, the battery ran flat so I replaced the battery. Now when I turn the key everything comes on but it won't crank. In the console there's a message "ESC inoperative". I took it to a Mercedes mechanic and he says he can read everything except the ECM, Transmission and Shifter modules. He check all wiring connections including communication wires.