I don't work for Roku; I'm just another user. I may have misunderstood your issue. Some people seem to think an update caused certain buttons to fail or that their remote is not the correct one because some buttons don't work - that's what I meant by "sort of".
If you just got the remote this past summer then I would think it's still under warranty. You might want to try: https://support.roku.com/article/208757058
As far as taking the remote apart, I've taken several Roku remotes apart and they're always a pain and each is different. There's usually one screw in the battery compartment and then you need to find the seam and it takes good fingernails to get the two halves apart. A credit card sometimes makes a good tool to pry it apart without damaging it.
However, if it's only a few months old I wouldn't expect dirty contacts unless something was spilled on it.
