Treat sand as a scratch risk. The safest first step is to avoid touching it with a brush, swab, or vacuum. Instead, use gravity and a blower.

With a fully charged battery, lock the mirror up for cleaning, remove the lens, and hold the camera so the sensor opening faces downward. Gently use a hand blower so loose grains can fall out on their own. If there may be loose sand elsewhere in the mirror box, clear that first before aiming airflow near the sensor area.

Then close the camera and make a test shot of an evenly lit white or gray surface to check for remaining spots. If needed, repeat.

If the grains do not come free easily, or if any appear stuck, stop there. Sand can scratch the sensor cover/filter, so professional service is the safest option—especially on a higher-value body. A manufacturer or reputable camera service center can inspect and clean it properly, often under magnification.

In short: blower only, opening downward, no brushing at first, and don’t force it. If it doesn’t clear quickly, send it in.