[Chris S.]

E82 here, but all parts are same as E90. Ran into the no start issue as a surprise. Would load up the starter, but not enough to turn over. Found the solenoid cable and hot wired 12v directly to it using a classic remote start setup. Ends up after tracing the wiring, the cable runs from the solenoid straight to the CAS. There are two connectors along the way, one under the charge pipe (for N55) and another in the ECU white box on the passenger side of the engine bay. The trigger start is meant to be temporary, but thanks to this thread I realized you could do it.

I took the CAS out of the car and started inspecting it. Found a burnt wire line that ran under the surface mount starter relay (G8FE-1AF-SL1). Going to try and repair it to see if the broken line is indeed causing the issue. Without a schematic, it's just a guess.

I have a used unit coming just in case. Then it'll be time to figure out how to either clone the old with the new or how to add my keys to the new and sync it with the DME. Seems like a lot more work than fixing a wire.