Wont start

Why do I get link error on my scanner when I plug it in? The scanner works on other vehicles. One fuse that is for start sig./BCM/i can't remember what else, but it has no voltage. Fuse is good, no fire on either side. Original problem was vehicle no start. Would not even turn over, security light stayed on constantly. Sometimes the whole insturment cluster would go dead. Car would still run. Pluged in my scanner "link error".I did a little research online about these symptoms, all said the body control module was bad.I got one out of a 2000 century like mine from the salvage yard. Installed it, made sure all the connections were good to the bcm. Turned on key all lghts on dash came on security light was blinking. Still no start, scanner did the same thing. The dash lights dont blink on and off like they did. The security light will blink for 3 minutes(i timed it), then stay on.I turned the key off for twenty seconds then tried to start it. Nothing, I did the same thing for four or five times, still no start.I tested the resistance between the two small wires with the key on 2.87 same as chip in key. So I think that is okay but I am just scratchin my head now. Could I have another problem some where else?HELP ME, HELP ME

For my $5 I thought I would get a different answer than TAKE IT TO A SHOP.I was a auto mechanic for 35 years, I know how to "TRACE" problems.I just thought you might could give me another direction to go for the aldl not working.A fool and his money is soon parted.