[Android Stick & Console AMLogic based Computers] unoaman:
Hello everyone,

<<DISCLAIMER>> The procedure is causing Serial no. wipe out and DRM issuse. Please follow this on your own risk. Or wait till solution is available for Serial no. and DRM issue

I've been spending a little bit of free time trying to research the downgrade possibility released Mi Box (Android TV MDZ-16-AB) from Nougat 7.0 beta to the stable MM 6.0.

It had been known that it is not possible due to locked bootloader of 7.0 firmware.

As researching i came across 4pda thread where one claims that its possible and have some steps to do so.

Disclaimer:

1. This is not my original creation. I am just trying to help others but capturing bit and pieces together from various places into a tutorial.

2. All credit goes to zalgy, MAKS.UA and hostel5 who posted the the original content on the 4pda.ru forums and I am just re-posting it here

3. If posting like this is not ok, moderators please let me know.

Warning: Do it at your own risk. I am not responsible for any damage to your device, laptop, desktop, you or your pet.

Link to original thread:

https://4pda.ru/forum/index.php?showtopic=777248

translated snapshot: in attachment

Steps:

1. Flash the box with Nougat 7.0 beta 1028 firmware.

once-7.0-1028.zip

for those already on the older Nougat Beta (build 924 or something): you will notice that your remote won't work in recovery, so you're unable to choose the *.zip file on your USB-Stick to update unless you have a USB-Hub and plug in a keyboard in addition to the USB-Stick.

There is a solution (thanks to the update guides for the other Miboxes):

Warning: I can confirm that this procedure wipes out user data and your box will be reset to factory default

a. create a file called "xiaomi_update" (yes, without any fileending) an write into it "--update_package=/udisk/update.zip".

b. Save it to your USB-Stick (FAT32 formated) and copy once-7.0-1028.zip also to USB-Stick and rename your once-7.0-1028.zip file to update.zip.

c. Plug it into your MiBox, boot to recovery with the known trick (press back and OK simultaneously while plugging in power) and the update starts all by itself.

After update the box may reset to factory default. configure the box and move to next step

2. Download below file and extract it. pull out rom3s.img and put it on the box internal storage in the download directory.

XIAOMIS3_FLASH_FILES_GLOBAL.zip

3. Connect the cable to the device , enable debugging.

3.1. Turn on developer options and ADB Debugging.

3.2. Setting> About> last item in the list> Click OK 7 times.

3.3. Go to Setting> developer option> Debugging> Turn ON​

4. Open the command line and go to adb and follow below steps

adb devices

Se if your device is listed and ready.

adb root

Gives root access

5. We need to backup for worst scenario

adb shell
dd if=/dev/block/mmcblk0 of=/sdcard/backup-3_once.img bs=1024 count=524288
exit
adb pull /storage/emulated/0/download/backup-3_once.img

to roll back to the original version, rename backup-3_once.img to rom3s.img and completely follow the whole instructions

6. Flash the rom3s.img file already placed in download folder

adb shell
dd if=/storage/emulated/0/download/rom3s.img of=/dev/block/mmcblk0

7. After flash is finished writing exit

exit

8. Reboot to recovery

adb reboot recovery

9. Download once-6.0.1-1304.zip and put it on a USB stick

In case above firmware gives problem then download MiBOX3S_USA_once_r454.zip from 4PDA.ru unrar it and put it on a USB stick

10. Insert the USB stick in mibox and flash the firmware as usual through recovery.

After flash is complete your MI box should be on Marshmallow now.

I can confirm that the remote does work in recovery if you are on 7.0 beta 1028 release.

Note: I have not tried it on my box yes as i am travelling and wont be able to access my box until end of this month. My box is on 7.0 beta 1028 release so i m half way and would be doing the other half as soon as i get access to my box

Please leave comments when you give it a try.