Best answer by Ryan S
Some TVs only accept certain CEC commands, so make sure OFF is one that your TV will take. Also, you may need to go into your TV's settings to tell it to allow being turned off by HDMI devices. What type of TV do you have? A model number would help the most with this.
For example, you'd be looking for Simplink - Auto Power Sync or Auto Power with an LG. For Panasonic Vierra TVs it's called - Auto Power / Power On Link / Power Off line. And on Sharp Roku TV or TCL Roku TV, look for 1-touch play.
‘Switch to TV’
The command "Alexa, switch to TV" should do the trick. If that's not working, try "Alexa, switch to TV on [room name]"