From the User Manual:

http://www.magellangps.com/assets/ma..._Manual_EN.pdf

"Connecting Power
Plug the end of the cigarette lighter adapter into a
12 VDC cigarette lighter receptacle in the vehicle.
Connect the other end to the Magellan Maestro as
shown. There is a wire catch on the side of the
cradle to run the power cable through to prevent it
from disconnecting. If there is power at the
receptacle, the Magellan Maestro will power on.
(Note: some vehicles apply power to the cigarette
lighter receptacle only when the ignition is on.)"

Assuming you were using the cigarette lighter for power, did you try
the lighter itself to see if it had power?

Magellan product support:

http://magellangps.helpserve.com/

Your problem doesn't seem to be in the FAQ list, so you could try
submitting a ticket he

http://magellangps.helpserve.com/ind...kets&_a=submit

There are at least 2 common standards for automotive cigarette
lighters. That's probably not the issue, though, since the sizes are
very slightly different, and you would have noticed that it didn't
quite fit.