I purchased everything to do the install for the w211 e55 with the basic non navigation head unit. Everything was going in great until the radio head unit was plugged in. The shop doing the install found the unit they sent me is faulty they get power and ground to the unit but will not power up. Messaged xtrons and awaiting a reply.

Now I decided it would be nice to have some tunes while driving and put the factory unit back in but that will not even turn on. Does the factory unit once unplugged and put back in need to be turned back on with star or am I missing something???

It shouldn't need to. I've had the stereo out of my E63 and it worked just fine when I put it back in.

I'm lost on this thing. I literally did not change a thing except strip a few wires to tie in power and ground for the new radio.

First thought: What did the shop fry during install that not only killed the new head but also your OEM system?

Well, I have to be honest. I never checked the fuse in the panel for the radio and that's all it was. I just jumped to conclusions and didnt stop to think for a minute.

Any chance the original xtrons head is just fine?
glad you found the issue.

I don't think so. We tried multiple times in the car andon the test bench to get the head unit to power up and got nothing.