Confirming your specific device or posting in the section for your device would be a good start . However, in the meantime if it's the U9-H to save you some additional time......
Have you tried reverting the change & it's still stuck in Chinese? Or, you just can't navigate back to it to find it? (I understand it's probably in Chinese but just in case you remembered the actual physical positioning of the setting you changed in the menus)
In the U9-H's settings, HDMI CEC is 2nd row down, 4th from the left, (look for the arrow in a box HDMI CEC icon). Enter & select the lowermost of the FOUR available choices. From there, ON is the uppermost option, OFF is the lowermost. Hopefully selecting whichever option isn't currently selected will revert your system back to normal. (FYI, the setting was ON by default on my U9-H & I've never adjusted it).
If it's another device, obviously you'll have to wait for directions from someone with your specific device.
Failing that as well, you may have to consider a full system reset. Instructions for that can be found HERE. Fingers crossed that the directions help & it easily reverts .
- If you have Minix Metro launcher, click on the clock to access the general settings (with launcher 3, it is the crank icon),
- down at the 3rd white pane containing icons you will spot a small round one, on the right side, symbolizing the Earth Globe, click over it
- then click the first line (it is the one to select the language) slide down the several languages. Yours will be readable there. Select it.
PS (EDIT): Easier, since you activated it through the HDMI CEC square (for the Minix U1 the location is the same as for the U9-H) you will notice there is a square with the mentioned Globe Icon just two places left of the HDMI CEC one. If you click it and scroll the many lines up, on the right side, that will allow you to choose your language as well!
I had that situation once, and just tried it again following your exact same steps, since as @ArcticWolf mentioned my box also has that HDMI CEC setting activated.