Originally Posted by SouthArk370Z

The antenna wire itself can handle a little corrosion with no ill effect. Not so much the electronics.

Inspect the antenna wire and make sure the corrosion hasn't eaten through it. If it is just a straight piece of wire, it can be replaced with another wire that is exactly the same length. Diameter of wire is not critical but much bigger than what is there may be difficult to handle.

I'd try cleaning the circuit board with a plastic bristled brush (eg, tooth brush) and some distilled water (just distilled water, no soap or anything else). Rinse well and let completely dry (a hair dryer set on low heat will speed the process) before powering up. If there is any corrosion remaining on the connector pins, it can be removed with a small wire brush or fine sandpaper.

Before re-installing antenna unit, you need to find out why the corrosion occurred in the first place. More than likely a water leak.