pretty easy to fix, just follow these steps:
It sounds like your camera has some hot pixels on its image sensor, also referred to as stuck pixels. To try to clear them, remove the lens and fit the dust cap to the camera body.
Now run a manual sensor cleaning routine via the camera’s menu. Leave the dust cap attached because you won’t actually need to clean the sensor. Once the cleaning function flips the mirror up and opens the shutter, leave the camera switched on in this state for about one minute.
Finally, switch it off, so that the shutter closes and the mirror flips back down. With the dust cap still fitted, take a few 30-second exposures in manual shooting mode at various ISO settings, then review the images at 100 per cent zoom on a computer screen to check that the hot pixels have cleared.
It may be necessary to run the whole procedure two or three times to clear the hot pixels. If they’re still stuck after that, you’ll need to send your camera for repair.
Dr. King Schultz: Auf wiedersehen. Bullseye.
Calvin Candie: You sir are a sore loser.
Dr. King Schultz: And you are an abysmal winner