My question would be if the new deck might be defective. I wonder if you would have the same problem if you try a different deck (only for the sake of testing and troubleshooting, not a permanent replacement for now). If the radio worked before, but not now, try another deck or the old one. If you get radio then, I'd say your new deck has issues and I'd get it replaced under warranty, especially if you bought it locally and not online. The one time I experienced this problem, about 25 years ago in ancient times it turned out that there was a bad connection INSIDE my deck! Strange, but not impossible. Manufacturers make mistakes too.
I wouldn't blame yourself or anything you did when you put the deck in (let your girlfriend read this!). I actually think it's the new deck, to be honest. If not, I would think that maybe the antenna wire got grounded out somehow like maybe getting pinched back up in the dash.
(Not that it matters, but I also have a Dodge Stratus.)
GOOD LUCK, man! I'll follow this thread and hope to see what you found out.