:( New Devo 10 arrived DOA, any experts around?

It isn't broken.
It is flashed with Chinese language and is telling you to move the switches to the safe positions (probably all up, with throttle all the way down.

I am not sure if reflashing with the latest Walkera firmware will get it back to English or not, but if not someone will be able to tell you how to do it.

Make sure it is working as expected before putting Deviation on it.

Ensure the FMODE switch is in 0 position, and try to lower the right stick to the lowest position too, because the tx might be setup for mode 1...

You don't need to test that the tx is fully functional before installing Deviation, but it is not a bad idea to make sure the menus work and otherwise is ok before installation. That way if you do need to return it you don't need to dealw with flashing it back. Once you install the extra chips you won't be able to return it, so make sure you don't see any issues with it. Getting the menus into English should not be difficult. The problem is that the manual doesn't tell you how many presses you need. You ned to do:
'Ent'->Main menu
'Down' to System menu then 'Ent' ->System menu
'Down' to 'Language' then 'Ent'-> Language menu
Select 'English'

But I don't have the stock firmware installed, so I don't know how many times you need to press 'Down' to get to the right menu.

Or you could just install Deviation immediately and test functionality with Deviation (again, just making sure switches/sticks work properly). It is unlikely that there are any issues with your Tx if you get the failsafe screen you showed in your video. But of course, in the end it is up to you.