Updated, but still cannot use.

Even use arrow key (not pressing the google assistant button) to click the screen on "speak icon" on search menu, it is not responding to any sound.
So this removes the possibility remote control button is faulty.

Try to on and off and on back the google assistant on the android setting page, the final setup page comes out something is wrong when finalising.

or google assistance is not supported yet on current android tv version?

Really no clue now.

Go to the remote control option or bluetooth section, no remote control is paired. But I can use the remote control perfectly, just the google assistance.

Then try to setup to pair the handphone for bluetooth pairing, it can pair, and I can use handphone to as remote control to control the button and on and off.

How to use the paired handphone as google assistance?

Can't find much info in order to setup or use the tv android system.