The problem has nothing to do with the Roku, and it's something that happens at more than Marriott locations. The hotel TVs almost all have a separate device connected to the TV via HDMI, and all volume control is performed by that box, not the TV itself. The TV volume is fixed at 100% and cannot be altered without entering a service menu that you can't do without the official TV remote. There is no way to control the TV volume control with any external device, such as the Roku. There's nothing Roku can do to change that.
The only way to use a Roku (or any other streaming device) on this sort of configuration is to connect to an HDMI in port on that separate control device, not the TV itself. And even then that device must have a menu option to select that HDMI input. In my experience, not all do. And many hotels install that separate control device in a complete inaccessible location. In one hotel I actually had to remove the TV from the wall to reach the control device, because it was installed within a hole in the wall itself and could not be reached with the TV in place. I carry an HDMI cable and adapter in my suitcase so I don't have to bury my Roku Stick back behind the TV.
I have visited a few hotels that actually place a HDMI input jack in an accessible location, such as the furniture near the TV. But most want you to use the apps they provide in the TV (actually in that separate control device) and perhaps pay them to watch something. At one hotel that I stayed at for four months I simply went to a nearby Best Buy and bought a Roku TV and replaced the hotel TV with my own. I had no interest in watching anything they provided, so no loss there, and I just shipped the TV home with me when my job detail was done.
Bottom line: Roku can do nothing to resolve this situation. All we can do is complain to the hotels about their lack of support for connecting guest-owned HDMI devices.
