I've been stuck for a few days on trying to install the drivers for my RX 460 4GB.
I've tried using AMD's support site on the error but I had no luck. All of the suggestions ended in Error 1603.
I've tried uninstalling and reinstalling using both the AMD Clean Uninstaller and the DDU.
It appears to be mainly a software related issue, so I'm pretty sure I don't need to return the GPU, at least not just yet.