My new Air2S already has a bad sensor.  I checked it out when delivered using it indoors due to bad weather.  Seemsed fine and calibrated well. Now I need to use it tomorrow so I thought I would run a quick test flight.  After just a few minutes I get the Rear Vision Sensor Calibration Error.  I ran the calibration again and the front and bottom go just fine.  But the rear sensor gives a weird rectangle that cannot match the required square view to calibrate.  So sad.  My Phantom 4 Pro lasted 4 years without an issue.  

I can share that the angle you are at is causing this. I also thought mine was defective then found the height and angle is different for the rear sensors. Slowly move the aircraft around until it "squares" up and the chevrons you show turn into 90 degree angles.
It takes a bit of touch to align them.
Good luck

Mission XR Posted at 3-9 15:25
I can share that the angle you are at is causing this. I also thought mine was defective then found the height and angle is different for the rear sensors. Slowly move the aircraft around until it "squares" up and the chevrons you show turn into 90 degree angles.
It takes a bit of touch to align them.
Good luck

I began the calibration because I was getting an error message. It had calibrated fine when I received it last month. I spent the better part of 20 minutes rotating the drone every which way and the rear alignment was never any closer than shown in the photo.  And why would the rear vision sensor operate differently than the front?

Hi, thank you for reaching out. We're sorry for the unpleasant experience. In this kind of situation, I'm afraid that you may consider sending the unit in for a proper diagnosis. You can contact our support team to start up a ticket at https://www.dji.com/support. Also, the warranty can be applied depending on the outcome of the damage assessment including the warranty period of your unit. To check the warranty period for each part, you may click this link: https://www.dji.com/service/policy. Thank you for your kind and understanding.

Already processed the return. Hope to get it shipped back tomorrow.

OSHP367 Posted at 3-9 17:35
Already processed the return. Hope to get it shipped back tomorrow.

Thank you for your response and we're glad that you are now sending the unit to us. Hoping to get it back as soon as possible for you to fly again your drone. Again, we do apologize for the inconvenience and please don't hesitate to reach us if you have other inquiries. Thank you for your valued support!

Mea culpa!!!

Mea Culpa!!!    I took the posters advice and tried the sensor calibration again.  He was right, the angle to calibrate the rear sensor is not the same as the Front and bottom.  I had to hold the Mavic at way more angle than I thought to get the square edges to line up.  I don;t know why it was so easy the first time and so hard the second time...but the ship is all calibrated and no more error messages!  Thanks to all.  

Glad to be helpful. Drove me crazy at first calibration due to the same experience.
Go Fly that thing!