Well, first you have to have a usb cable that can plug to a tv, for example, my tv has a usb-c port that I could use for this purpose. Alternatively, you can use wireless debugging over the network, though that can sometimes be cumbersum to set up, so yeah.
Note: I suppose you have adb installed, as well as the usb drivers for your device as some of them use proprietary things to connect to the debugging sessions, so I recommend you consult your tv's manuals, sites, forums, or whatever for more info.
So, with that out of the way, first you have to have a sighted guide in order to do this, haven't found a way to do it unless, by some miracle, usb debugging is enabled on your box, chances of it happening are practically nill, but anyways.
So, once you turn the thing on, press the home button on the remote. It would be weird for it to not have one, but anyways, press that to go to the home screen.
Once you're there, go to settings. If you don't see developer options there, you have some to go through still, but it's not so paneful. So, once you're in settings, activate the about device option and press select button 7 times on the build number, you'll know if you're pressing the right one, since some text will keep flashing on the screen reminding you you will be a developer soon or something like that. Once a message like you are now a developer! went up in flames on your screen, go back to settings. A new option just appeared in there, sneeky developer options, right?
Now, once you're in there, hit that trackpad for all your worth untill you arrive to the debugging category, then go and hit that usb debugging switch with all the remotes buttons...nah, just kidding.
Anyways, now you enabled the usb debugging, let's make sure it worked, right? So, plug that usb cable in the tv and your computer, then, at a command prompt, type adb devices
Now, in any normal situation, a popup should appear on your tv screen. In that case, check the always allow for this computer, just for convenience, then activate the OK button. At this point, your tv should be able to be issued commands from your computer. To test that, type adb devices in the command window again, it will display your device serial or whatever else your device goes by in this debugging communication. Whatever it might say, if device, in stead of not authorised, is displayed at the end of the output, then you can go forward.
Now, just type this command as given, it sets something like the android equivalent of the windows registry, this version sets the accessibility on, and the talkback service as default accessibility service, because some brands have the accessibility menu for default which, as you could guess, is not accessible at all. So yeah, copy/paste the following command as given in the command prompt, then hit enter to send it to the device.
adb shell settings put secure enabled_accessibility_services com.google.android.marvin.talkback/com.google.android.marvin.talkback.TalkBackService
If you don't hear speech, but earcons are fine, plus someone sighted can confirm that the talkback tutorial is open, either you might not have a tts installed or the one you have doesn't work with your system language. In that case, try installing an engine called eSpeak from the playstore. If that doesn't work or no window appears at all, you might be royally scrued, but write here anyways and I'll try helping as much as I can and know my self.