Worth checking first: ask the body shop whether every sensor connector behind the bumper went back on, and look for an uneven gap along the bumper line that signals a shifted carrier. If FCW is still showing, the radar needs recalibrating.
On a Nissan that means removing the front badge to reach the sensor, and on 2022-on Qashqai and Pathfinder variants, a workshop with Nissan Consult 4 access (the popular aftermarket tools are locked out on the newest cars). The radar calibration runs as a dynamic drive procedure.
It's a fixed £349 through our network: scan, calibration, badge refit and certificate, all included. If the scan shows the radar was damaged in the impact, you'll know the cost before any work goes ahead. There's no charge for the diagnostic if you decide not to go ahead. The full procedure is in our ADAS calibration guide.