Still got no response from the seller. Would give him more time until Tue as the 1 week warranty is over on Wed.
Firstly, I already checked the item physically and every physical things were fine.
Secondly, the defect is not outside where you can detect it on the spot right away. It was on the sensor. And it is not dust that you can use the blower to do a bj easily but hot/dead/stuck pixels. You have to take photo of dark objects or night time in order to see those hot/dead/stuck pixels which could not be done while I viewing the cam in daylight.
Thirdly, i'm new in photography hence this is the first time heard about this issue, so I was not knowledgeable enough to ask the seller to check for dead pixel beforehand.
The day before yesterday, I sms the seller to let him know that I found a dead pixel on the sensor and asked whether he can help anything on this. He answered me that he dun think Nikon will do anything for just 1 dead pixel. So I was fine with this reply, cos I thot i can live with it. But yesterday, I took photo with slow shutter speed and small F (~2-3), I found 4 more, very obvious, you look at the pix and can see already. My fz advice me to check again using software. You know wat, I saw a sky full of stars. There were 20 dead pixels in red, blue, white,... omg, like a rainbow.
Then I sms and told him nicely about that and suggested he take it back and use it as his back up cam. He refused and claim that he checked his pix and didnt see anything wrong. I sent him the photo I took and result of the software for him to see but have not received reply until now.
The point is, if I didnt have his words for the 1 week warranty, I would not complaint anything cos it is the risk of purchasing 2nd thing. But once I already had it and put my trust on him, I want to claim for my right...