"Rear/Rear Corner Ultrasonic Sensor" has "fallen through”

My left side "Rear/Rear Corner Ultrasonic Sensor" has "fallen through" (US 2023 CX-50 loaded Turbo) , and now only a hole exists, where it used to be. Believe it may have been pushed through via a non-brush car wash. Is the "access door" to the right of the sensor, the way to access the sensor? Any trick in opening the access door? Looks like a small screw driver head might open it, but I'm not mechanical and don't want to do anything stupid. Yes, because of the sensor having fallen into the "bumper well", it is a real challenge to smoothly back up without the car suddenly coming to a jolting stop. Just want to be able to pull it up to the hole, so I can get the 50 to the dealer. (Still under warranty)

Any help would be greatly appreciated.