Units 4 & 9 are most likely best for parts unless you think you can fix them. They all state if they work or what is wrong with them. All keys were tested on the ones that do work apart from 4 of the Function keys ontop.
The Microsoft Surface Keyboards are designed specifically for Microsoft Surface Pro 3, 4, 5, 6, and 7 models. These keyboards feature a sleek black design with a flat key layout and backlit keys for enhanced usability in any lighting conditions. The magnetic closure ensures a secure fit, making it convenient to attach and remove from your tablet. These OEM keyboards are perfect for those looking to enhance their Microsoft Surface Pro with a reliable and high-quality accessory.