Ok.. If your keyless was working in there before you let Best Buy touch your stuff (what were you thinking??
) Chances are the factory radio was back behind the console or something like that.. If it was the stock keyless, you are correct when you say the factory headunit runs the keyless.. Chances are the idiots at Bestbuy removed the factory head unit and your other one as well or there is no longer power going to you old head unit and it is still back there somewhere. Id call Best Buy and find out exactly what they did! All I can say is you have a 99.9% chance that they screwed something up for you.. They always do..
Good luck..