If your remote has a Vudu button and your Roku keeps going to Vudu obviously the button is stuck. Does it happen if you remove the batteries from your remote? You can always use the Roku app on your phone/tablet as a remote, take the remote apart to try to fix it, get a new remote, or rip the button out.
If your Hisense TV is still under warranty you should contact them for a replacement remote.
Where can I get support for my Roku TV™? | Official Roku Support
Roku Community Streaming Expert
Help others find this answer and click "Accept as Solution."
If you appreciate my answer, maybe give me a Kudo.
I am not a Roku employee.