Radio and power antenna worked fine, until mechanic worked under the dash. Now radio appears to be functioning, but the antenna doesn't extend. Where are the wiring connections and fuses that could have been affected by working under the dash.
Check the antenna fuse with a test light or a voltmeter. Then open the trunk and go behind the side panel where the antenna is. Check for power on the relay that's mounted on the antenna. Check to see if the motor is running all the time. The antenna mast may be broken. Try to pull the antenna button up. Start here