Could you provide more details please about what you mean about wanting to register your product. Do you mean that the D435i is not being detected by the computer, please?
If you mean registering the purchase of the camera for warranty purposes, that is not usually required with RealSense cameras. The policies for camera returns can be found halfway down the page linked to below in the section headed 'Returning a product'.
https://store.intelrealsense.com/customer-service/
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Also, please note that the RealSense forum has moved to a new location, so future questions should be posted there so that the Intel support team can respond. Thanks again!
https://support.intelrealsense.com/hc/en-us/community/topics
