Hi Noel Shorts,
For the Surface Book model 1835, Microsoft doesn’t sell the keyboard/base or its battery as a standalone replacement. The supported option is to use the Surface service and repair process as per guided above by the Q&A Assist, where available repair or replacement options can be checked based on the device’s status.
If you prefer in‑person support, you can also bring the device to a Microsoft‑authorized service provider, who can help assess the keyboard/base and advise on next steps.
I hope this helps get your device back up and running soon.
Thank you for your patience and understanding.
Best regards.