Blue spots in my photos?

So, I just bought a used Nikon D90 from someone on ebay and I was testing out the camera and noticed that when I zoom in on images there are always the same 3 blue dots in ever picture. I did some research and found that it is either dust or dead pixels. I was told to try using different lenses and seeing if the dots were still there. I tried a few different lenses and the dots were still there. I read online that if you take a pitch black photo and the dots are still there than that means that they are dead pixels, not in the screen itself, but a problem with the light sensor. Is this correct? The dots are only seen when I zoom in on the photo so it's not the LCD screen. I used the image sensor cleaning feature and the image dust off feature and neither of those helped. I also read online that when this is a problem with a camera that most professional photographers get a new camera. I'm not a professional photographer but I did pay a lot of money for the camera and if it is such a problem that it would make someone want a new camera than I will want to get a refund for it. The dead pixels are even visible sometimes when I don't zoom in, depending on how they blend in with the picture. They are always the same color, blue.
So, my questions are:
1.) are these dead pixels or something else?
2.) can the problem be easily fixed?
3.) should I send the camera back and get a refund?
Anything else I should know? Thank you in advance.
p.s. The guy who sold it to me said that there weren't dead pixels before he sent it. It was sent with shipping insurance and it is still under Nikon warranty.

From what you described, I would say that you have some bad pixels. You did all of the appropriate tests. Depending on the location of the problem pixels, you might be able to live with it. Sometimes you will crop them out of the image and sometimes you can fix them with the healing brush. The only way to fix this in the camera is to get a new sensor installed. Not cheap. I don't know if the warranty is transferable, so read carefully before you consider sending it for repair. Personally, I'd ask to return the camera. You can show the seller samples with the hot pixels.

They are dead pixels, called Hot pixels. Dust on the sensor does not glow, and are never a single pixel. They can only be fixed by replacing the sensor. Professionals replace their cameras when this happens because it costs about the same as repairing it. The nikon warranty requires proof of purchase. If his sales recipet is less than a year old and doesn't have his name on it anywhere you can have him send it to you and you send it to nikon. Its between you two, and whether you think it was a good enough deal to make it work keeping the camera and going through the trouble and expense. You can keep the camera, fix the hot pixels in editing, and negotiate a partial refund with the seller. You can send it back under your paypal protection and get your money back and lose the cost of shipping it back. You can try to go the route of claiming the insurance on the shipping, but I think only the sender can do that. If you paid a lot for it, you paid too much anyway. They only sell $900 new, $700 reman for the body, and the older 18-70 is a much better kit lens than the 18-105 that came with the d90.

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