[Injera]

Worked perfectly. The only question they asked was:
"Was the package was open or was it damaged while it was delivered?"
And I responded
"The outer package was not open. The inner package is dirty and did not come sealed shut and was crushed a bit"

Good work with your response and of course, the SE Itself.

They told me to return what I received for a full refund.
Now my question is can I get away with keeping the wireless receiver? Or should I return everything except the mouse and try to buy a separate receiver.
I told them upon opening the package the mouse was missing but didn't elaborate.

Why go through the hassle of purchasing a receiver?

Just keep It.

My thought process is that since I claimed missing mouse (manufacturer error), it's unlikely that the receiver inside the packaging (it has a specific smaller cardboard packaging within the box) was also missing. But I'm sure their returns checks aren't that thorough to connect the details of chat logs with whats returned in the box.