There is no way to have real-time maps without the gps working,
because the unit has to know where the boat is in order to determine
which map to display.
Have you thoroughly checked your power connections.
Fully charged and load tested your battery to be sure you have
a good power source? If it is not, I'd wire the unit directly
to a battery (not through a fuse box), to get the best connection.
You can use a known good car battery to test it.
I'd unhook the cannonlink for now and see if you can get the
gps working. I don't know if a malfunctioning cannonlink could prevent the
gps from working, but who knows. Check the connectors on your gps wire.
If your unit is under warranty, it may not cost you anything
to get it fixed. Call Humminbird customer service 1-800-633-1468.
If you do have to send the unit in, ask Humminbird to send you a
mailing label. I think the repairs are just a flat fee. I think turn-around
can be as quick as a few days to two weeks. Call customer service and
they can tell you exactly what it would cost, how long it would take,
and may suggest other things for you to try.
Good Luck.