Audio Systems: Alpine TDM-7532 dead, alpine car stereo, alpine tdm 7532

Question
Hi, Dan,
I was going to give it away my nice, old Alpine car stereo/CD changer system, so I attempted to power-up off of a good 12V source, like I've been able to do before, and for no reason I can think of, it is now completely dead (in-line fuse is good) like a relay somewhere is fried, or something.  I didn't see any smoke leak out at any time, and opening it up reveals no obvious damage (and no, it never got wet).
I am told the detachable faceplate has no security code
(like Kenwoods have, apparently?), but that even this would not keep the unit from getting power.  The electronics for the faceplace are in a little tin box behind the LCD display, and gives no clues.
I've never had any problems with it before.
Any ideas?

Answer
Make sure you have the polarity correct.  There is a diode to prevent damage if connected backwards.  Also, there will need to be 2 wires connected to the positive side.  One for power and one to switch it on like the key does on the steering wheel.
Dan