Beam Control of TV Using HDMI ARC Connection

Trying to use a Beam to control a 70' Vizio TV with the HDMI ARC connection. Using Alexa, I can turn on or off the TV, and control the volume of the TV. However, if I turn OFF the TV using the Remote Control, the Beam can not turn the TV on and in fact, the only way to turn the TV on is to reboot the TV by removing the power cord. I have searched for any Power Control settings on the TV, with no success. I also spent an hour on the phone with Sonos support, with no success. Any suggestions?

For the bolded part, do you mean "the only way to turn the TV on by voice control is to reboot the TV...". If the TV just won't turn on at all, that's a problem with the TV. Anyway, assuming you mean by voice, then my first guess would be that there is another device connected to the TV by HDMI using CEC control, that is messing with TVs setting. We've seen this happen for several other scenarios.

To test if this is the case, unplug all HDMI devices but Sonos, reboot the TV, and see if the issue still occurs. If it does, other devices are not the issue. If it does not one of the other devices is the issue. You can plug those devices back in one at a time, testing in between, to see which one(s) is the issue. Once identified, check that devices settings to see if you can turn off CEC control. If you cannot, look at getting a CEC-less HDMI adapter that will block CEC commands between the device and the TV.