The radio probably needs a code but it would display CODE if waiting for the code. They probably disconnected the antenna power wires to keep it from trying to retract continuously. Replacement masts are available for OE antennas.

Did the car come with service history documents? If not, checking and replacing fluids and filters is a good way to get to know the car. Authorized and bootleg CDs of barely passable factory service manual scans are available. Or spend the money on printed volumes if you’re a DIYer. Oddly, the CDs don’t include transmission service volumes.

Mike Murrell on this forum was particularly helpful when I had a ‘91 300SE.

Sixto
98 E320s sedan and wagon