I had the same issue with my Furrion 49" outdoor TV (model FDUP49CBR). I did some searching online and found a code that works. Choose 'Curtis International' as the television when selecting the TV. I think it was the 3rd or 4th code that muted the music playing. Once set, I was able to control the power and volume of my Furrion TV using my Roku remote control.
We just purchased a Furrion outdoor tv and are planning to hook it up with Roku. I read that the HDMI connections are sealed in the back. How difficult is this to access? Can you leave your Roku in all the time? Do you use a Roku streaming stick?
It is very easy to open the door to access the HDMI ports on the Furrion TV. I mounted the TV with a Furrion outdoor mount and still can access the door & HDMI ports. I was able to easily fit the Roku stick in the sealed door (using the built-in USB port on the TV for power), but had issues with my WiFi signal. I ended up purchasing a 3-foot HDMI extender and have the Roku stick sitting on top of the TV. This helped with the WiFi signal as well as allowed the remote control to function better. I keep the Roku stick plugged in all the time, but the TV is covered underneath my outdoor pavilion, so I don't worry about it getting wet or the sun hitting it directly. I've only had it a few weeks, so not sure if I'll leave it plugged in all Winter.
The Roku stick is plugged into the HDMI port on the back of the TV. The USB port on the back of the TV provides the power for the Roku stick. The Roku stick comes with the USB cable. You run the USB wire from the Roku stick to the USB port on the back of the TV.
The Roku stick came with a USB extender. I initially used that cable and it worked fine. However, I wanted less exposed wires (given this is outdoors), so I just dug out a longer USB cable that I found laying around my house.