[Xiaomi Mi Max Guides, News, & Discussion] shuckeru:
So basically, I got a new Mi Max helium 3 days ago, wanted root, and the most recent stock stable rom. Looked on the threads, guides are not up to date, or are for unlocked bootloaders, or are just plain unclear. SO HERE'S ONE THAT WORKS! (at least for me) I've essentially mashed together a few guides, and found really helpful posts. I'll go step by step for everyone to follow.

Your data will be wiped. proceed with backups (whatever you can do)

1. download MiFlash Beta

2. extract the installer from the downloaded zip

3. install MiFlash Beta (it should install drivers for you.)

I was met with a warning on unsigned drivers or similar. just make sure to select "install anyway"​

4. download and unzip this prepackaged zip for flashing in MiFlash TWRP 3.0.2.0 for helium.

5. download and unzip the fastboot version of MIUI v8.1.3.0 Global stable for Helium

6. download and unzip recovery flashable MIUI v8.2.1.0 from this thread.

7. download the newest TWRP .img from twrp's site .

I KNOW it says hydrogen, but this official post states it is for both. And if you try looking at the Helium link it doesn't have the latest TWRP. trust me on this one. it works fine. Only download the hydrogen 3.1.0 version.​

8. download "universal boot.img patcher.zip" from this thread.

9. download latest SuperSU recovery flashable zip.

we need to modify the ROM to be able to work with a locked bootloader as suggested by this post.

10. go to the folder you extracted the prepacked ROM you downloaded in step 6

11. zip up all the files except for the "firmware-update" folder

Now that you've got all the resources, we can go to a version of MIUI that does not have security patches and allows custom recoveries with a locked bootloader, then upgrade from there.

12. Run MiFlash Beta as administrator

13. Turn off your Mi Max Helium

14. hold down Vol + and Vol - on your phone then plug phone to computer via USB while holding the buttons down to enter EDL mode. you should feel a short vibration and then a black(blank) screen.

15. click on the "refresh" button in MiFlash

you should see a new entry for id: 1, device: COM**​

16. click on the "select" button and navigate to the folder which contains the extracted files of the fastboot MIUI v8.1.3 you downloaded in step 5.

17. click flash and wait for result to show "success"

now we need to re-enter EDL mode to refresh EDL​

18. hold down Vol + and Vol - and Power buttons on your phone with the USB cable still attached to the computer. again you should feel the vibration and then black screen.

19. refresh MiFlash

you should see a new entry for id: 1, device: COM** again​

20. click on the "select" button and navigate to the folder which contains the extracted files of TWRP 3.0.2.0 you downloaded in step 4.

21. click flash and wait for result to show "success"

additional info: if you have issues trying to flash, also perform the instructions from this forum post.

22. hold down Vol + and Power button to boot into TWRP recovery. you should feel a slightly longer vibration.

at this point you should see the MI logo and it will take a while before it changes to TWRP's logo. once you see the MI logo you can let go of buttons. if the MI logo only flashes quickly and disappears, then try flashing a older version of MIUI instead.​

23. when TWRP boots, it will ask, and you should keep system read-only at this point.

24. format the data partition. important

25. check if your preferred method of copying/pushing files can be done from the computer

26. copy/push the newest TWRP img you downloaded from step 7 to /sdcard

27. install the new recovery.img

28. reboot into recovery and keep system read-only

29. flash the prepackaged ROM you modified in step 11

30. flash the boot.img patcher you downloaded in step 8

31. flash latest SuperSU.

32. DO NOT REBOOT.

33. mount /system

34. delete /system/recovery-from-boot.p (or similar)

35. you may reboot now.

36. PROFIT!

Based on the fact that we used a boot.img patcher, theoretically I could use the official latest roms as long as we patch immediately after flashing the recovery version instead. I've not tried this, but you're welcome to.

If you get a softbrick (Mi logo flashes then black screen) just use MiFlash and flash any Fastboot version official rom. (or the v8.1.3 for convenience sake) that'll reset everything.

Thanks to these following guides and threads, and i implicitly hereby thank creators of the prepackages/tools they link to.

[GUIDE]ROOT/TWRP/MULTIROM/Cm13/RR on Locked Bootloader + Hardbrick Recovery by [MENTION=219885]DoomSlayer[/MENTION]

source for boot.img patcher thanks to this post by [MENTION=4790877]avi3230[/MENTION]

[ROM] [HELIUM] MIUI 8 Global Rooted by [MENTION=1397125]ajsmsg78[/MENTION]

and [MENTION=631273]Chainfire[/MENTION] for SuperSU