Update... Put the ECM and SKREEM back in and fired the car. It started and ran. However, I had a very rough idle, the car was missing and check engine light came on. I cleared the 2 dash lights (BAS and ABS maybe they were) by resetting the steering wheel with the crank-to-crank and back to center recalibration. I traced the rough idle problem wiggling on wires and those 5 or 6 connections that get plugged into the ECM. Pressing down on the 2nd to the furthermost rear (the first one that has the "flip to release") and it returned to a smooth idle while pressing on that one. I pulled that one and checked connections, pushed wires down into it couldn't find anything lose so I plugged it back in and problem fixed. Running perfectly. I must have had a bad connection there. I cleared the check engine light that was probably thrown due to the misfires by disconnecting the battery again for a few minutes and then reconnecting and re-firing.

Anyway, great job by Josh at Mercedes Swap Shop! Can't recommend the service he provides highly enough. He even repaired one of my 2 keys that wasn't transmitting to lock and unlock the doors for free. Thank you Josh! (probably that battery connection he posted a video about how to fix).