Can I replace the power button?

@tylerlemieux yes, you can. First, you will be looking for a power button flex cable. It looks like this (example only, not an endorsement) Samsung calls those the Side Key PBA and here is where it is located

Now, even so there is no specific guide, use the ones from here. Samsung Galaxy Tab S2 9.7 (2015) They will get you into your tablet and you can then figure out how to do the rest. If in doubt, just post some-good pictures of where you are stuck etc.

Adding images to an existing question

While you work on your tablet, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has a device with the same issues as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.

Repair is War on Entropy!