07CL550Benz

Hey All, so I've got an issue where my car will start up fine when cold, but once it's been driven for a few minutes and warmed up, it won't start up again until *something* cools back down. I had the local Mercedes dealership take a look at it and the tech said with 80% certainty that the ECU had gone bad and was causing this issue. He noted there is a LI (service bulletin) that addresses this issue L(54.21-P-052569. He noted that upon attempting to start the car again the fuel pressure was very low (around .5BAR, should be about 3.6BAR). Apparently this can be caused by something heating up in the ECU and then essentially not sending the correct signal to the fuel pump until the unit has cooled down. So my question is assuming he is correct and the ECU needs to be replaced, what are my options? I'd prefer to find a used one maybe from a vehicle being parted out. Does anyone know the process of having one programmed? My car is a CL550 but I'm assuming one from an S550 or W221 would work. Any help on this?