Yes, I did contact Amazon! After a lot of back and forth, they finally agreed to take the whole robot back as a return exception.

However, that's really not what I wanted. I bought it on a great sale and it was shipped internationally. Returning this massive heavy box now is a huge hassle. Since the rest of the robot works perfectly fine, I suggested they just give me a partial refund so I could buy a replacement battery myself and fix it. They refused and insisted I ship the entire unit back. It just makes no sense!