Performance Upgrade to my ECU

So raise your hand if you know what your vehicle ECU is! hmmm, I don't see many hands.
Well, I decided to send my ECU for my CLK off to Speed Tuning USA for a rather inexpensive performance upgrade. It's a quick turn around job where you overnight them a part, they program it and send it back and you have it the following day. Well, this is what I did, and on the day I got the part back I drive back up to Austin from work, in a friends car, plug in the 5 wire harnesses that go to the ECU and attempt to turn the key. THEN... Nothing :( it won't start and I"m supposed to be driving home to Louisiana in like 5 minutes. Arrrrggghhhh
So, I packed my clothes in my friends car and left my Benz in the driveway. I took the ECU home with me and mailed it off via UPS on Saturday. I'm waiting for the part to get back to me either today or tomorrow since the guy send it via USPS and I just hope my car starts. It could expensive if not... tow truck, mercedes dealer... yada yada yada
Keep your fingers crossed.