On the MiTV 4S 55" (MSSP3, "machuca"), you can use adb oder usb! You need an usb a to a cable, enable adb in developer options, and connect your laptop/pc to the usb port marked here:
(Only this one port works, others don't)
I am just leaving this here. What I am currently struggling with:
- finding info on the bootloader: is it locked? (most likely)
- booting to fastboot. Have not found a way yet. "reboot bootloader" (over adb, directly on the tv, or through the recovery, doesn't matter) just reboots android.
- finding any firmware for this device. I really don't dare to do anything, because I could easily brick something and never be able to restore it without rom file. I never had this problem with any android device, ever! Does anyone know where to get one? Tried the "XiaomiOTA By PaXaN86 4.0.exe" from 4pda, could not download anything no matter what I tried.