I sold my working, good condition 5D Mark II to another photographer in a facebook group. Paid by paypal, and mailed via UPS with insurance and tracking. The camera was in a good working condition when sent.
A few days after receiving, the buyer said: "...there's something wrong. None of the pictures are in focus. I tried multiple lenses and even calibrating them. I believe the cameras autofocus is broken."
This was not an issue when the camera was sent, and I do not know what could cause this, perhaps something the buyer wittingly or unwittingly did to damage the camera.
Attached are two images sent to me by the buyer, one is of the National Park Forest sticker and one of a car.
Any ideas on how to fix or resolve this? Or thoughts on what could be happening?