I need a battery. The one that came with it is dead. I'd also like to buy spares... Why can't I do this on DJI's site?

If you have a defective battery contact DJI support. I would hope they would not make you send back the entire Robomaster after you assembled it. Spare batteries will likely be available soon. I just received both the Robomaster and gamepad today.

Hi, Thank you for reaching out and we do apologize for the inconvenience. As of this moment, the Robomaster S1 battery is currently not available on our store website and if you are having trouble with the battery we highly recommend you to contact our support team at https://www.dji.com/support to start up a ticket. Also, you may refer to the link below for the available spare parts of the DJI Robomaster S1 on our store website. Thank you for your kind and understanding.

https://store.dji.com/category/robomaster?from=menu_products

That link is not for RoboMaster S1 parts (I WISH!) but rather the full Robomaster used in competition.   If the parts in the link can be used on the S1, I'd like to see some documentation.