I just changed the conductor plate
Now car won't start. All electrical components work just wont do anything when u turn the key

 

First try the "Mystery No Start" solder job on the RCM

 

Checked RCM , everything is fine.
Disconnected battery cables and touched them together for 20 sec. Still no start.

 

You need to clear all the codes that have been set; That scan must get into the transmission/Mercedes codes, a common generic OBD II scanner will not go deep enough. Clear all your codes then try to start the car; still no go re check any set codes.

 

We can assume you did not harm and did put the electrical plug back in?

 

Yes I plugged it in without damaging it

 

For the MILLIONTH time, do this:

Get in car, close door (or don't, I don't care.)
Turn key to start - does it engage starter?
If not, relax key to "ON".
Wait 30 seconds.
Does engine cooling fan warp up to high speed?

If so, it IS the RCM. PERIOD.
If not, we have some more homework to do..............

 

I went out to do what you said and the car started this time. I shut it off and on several times, keeps starting now. For most people they would think great problem solved but for me it just worries me.
So now what do I do? I'm assuming it's the RCM but not sure.

 

I have one more question.
The two electrical plugs under the tyranny, I didnt realize they were the same or I would have marked them . How do I know which one goes where?

 

Sure sounds like RCM to me. Having a spare is a good idea, I think I'd order a new one and put it in the trunk!
Then just wait..............