'97 Caravan Radio Question

Dear Anyone Who Can Help,
I had the brilliant idea to replace my factory installed 1997 Dodge Grand Caravan tape player with another factory installed 1997 Dodge Grand
Caravan tape player with cd player that I bought cheap on eBay. I had never replaced a radio before, but figured it couldn't be too hard since the "new" player was built to fit exactly into my car. I looked on the web to see how to take the radio out of my car and learned where the screws are. I successfully took off the plastic and all the securing screws. When I took the radio out, I disconnected (in this order), the antenna, the grounding wire, and the two wire plugs. I then attached the "new" radio/tape/player (in this order): wire plugs, grounding wire, antenna. When I turned on the power, nothing worked. I then I wondered if somehow I had blown a fuse, so I checked the fuses, but everything was ok. I then decided to put my original radio/tape player back in, thinking that maybe the new radio/tape player/CD player either never worked to begin with or that maybe it wasn't compatible with my car. I did it in the same order that I did the other. Now my original one wasnt working either! So I read the web instructions that I had downloaded a bit more carefully and only at this point did I realize that I should have disconnected the car battery before removing the radio. I then disconnected the battery and tried the whole process again, figuring it wouldn't really do any good, but also thinking it could hurt at this point. Not surprisingly, it didn't help. When I turn the car on and then turn on the radio (I have the original back in), there is a quick powering click sound and then the radio goes totally dead. I get this reaction only once. In order to get it again, I have to turn the car off and then on again. Then I can get this reaction once more. And so on and so on and so on...
When I looked on eBay again for another radio to install (hoping that the radio was hurt in the process but not the car in general) I notice one seller saying that he would send the VIN number with the radio so that the local dodge dealer could get the security code when installing. Does that have any relevance to my problem?
Fortunately, the air conditioning was not hurt in the process, but the locking system was. Before I did this work, the electric door locks worked whether the key was in the ignition or not. Now the electric door locks work only when the key has teh battery engaged. I'm assuming that happened because of the "work" I did, but I'm not sure.
So, here are my bottom line questions: Do you think that I blew the two radios by going through the process I did as described? Or did I blow the radios AND something in the car? Is my locking problem directly related to what I did? If I blew something in the car, might it be as simple as a fuse that I have not located? And If I blew the radios, do you suppose they are beyond repair? Or might there be a fuse in the radios that I could replace as well?
Thank you so much for putting up with my auto idiocy and the long list of questions resulting from it.
Any advice would be MOST welcome!
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