The on switch button functions just sometimes

It is possible, but you have to remove the screen, which is pretty fragile. Me and the company I work with usually don’t mess with Surface Pros, they seem to have poor designs for repair. If you want to try it, you can go to eBay probably to get the part. You would need a lot of heat, using a heat plate or heat gun, and tools to remove the screen. Once in I don’t think actually changing the power button is that hard.