The Yi 4K plus has 2 operating systems one of which is Linux.
This is a first draft of what may be a long document as I discover the secrets of the Yi 4K plus. You can hack around just by placing files in the root of the microSD card. The big one is autoexec.ash this can poke different settings into camera ram . To downgrade just remove the file from the card. The files are plaintext with single carrage return (unix linux osx default. notepad++ can produce these text files on windows.
To start with i created a blank file with 1 newline and saved it as
system.pref.download
This downloads the system prefs from the camera.
system.pref.upload
uploads preferences to the camera (just rename the download file).
The above file is basically a standard prefs file, with nothing special done to it.
The empty system.pref.download file gets written to when the camera boots up.
https://github.com/irungentoo/Xiaomi_Yi_4k_Camera
Probably the biggest source of knowledge on Yi cameras I can see me spending hours on this repository