I’ve just bought a M8 from the same place, although the M8 box itself is very good, it does not respond to anything from the original remote control. Fortunately I bought an extra Remote Wireless Qwerty Keyboard as an extra, it is responding to that but I have to move my arm all over the place to get the mouse to move where I want it, Very frustrating and there is no way to turn the box off other than to pull the cord out.
I might go back and change it for a T8 tomorrow, if they have them in stock.
It must be faulty, but if you want to put it through it's paces before returning, you can adjust the airmouse pointer speed, settings/ other/ more settings/ language & input/ Mouse/Trackpad/ pointer speed.