Razer Deathadder Chroma:Invalid Product Serial Number

Hello, I may have a small issue.
I recently bought a new mouse, however I can not add it as a device in Razer Synapse because of "Your product is no longer covered by Razer's Limited Warranty". I know the mouse is older version, but since I bought it a month ago, I still expect it to be connected so I could change it´s sensitivity to my preferred sensitivity.
So I ask what can I do to contact support/get it working so I could change the DPI of my mouse.