Just a (dumb?) question to the OP: Does the radio tray have a BNC connector
for the coax cable connection? Can you try a piece of short coax connected
to a 'portable' antenna attached to some type of ground plane? If this setup
works, then you'll know it's somewhere in the original coax connections, if
the radio still doesn't receive, then it would be a different connection
problem.

Are you sure the radio itself is good?

If you have already tried this, disregard...