[Xiaomi Mi Max Questions & Answers] morizuki:
Me and my wife has the same Mi Max Pro and I flash an EU Rom for both of us. I noticed that we have the same Bluetooth Mac Address, I searched everywhere to see if I can find where I can edit the Address, but it seems there's none, Screenshot of our Bluetooth Mac Address is attached below

So I tried experimenting it, I flashed the Official Global Rom for Mi Max Pro to my phone via EDL Mode using MiFlashBeta. After successfully flashing, my bluetooth address is now back to the original Mac Address, meaning it was fixed, and so I thought it was fixed, I flashed the TWRP via MiFlashBeta (because I don't want to unlock my bootloader) and Boot on the Recovery. As it says I can't do anything because I have to format the data to removed the encryption. So I format the data and reboot to system. This time, it is stuck on the Mi Logo and it won't continue, so I tried rebooting to Recovery, I made a backup of the whole rom just to be sure including the EFS Partition.

Then I flashed the EU Rom. I even tried restoring the EFS Partition just to be sure if the Bluetooth Address will be fixed. But after booting the Bluetooth Address is the same as before, the 00:00:00:00:5A:AD So it means somethings wrong with the EU Rom or during the Formatting of the Data.

Now I tried flashing the Official Global Rom via Updater with a TWRP. Recovery. And now the Bluetooth Address is fixed again. But my TWRP is gone again.

Does anyone know how to fixed this?

EDIT: Solved it by experimenting.

I'm using a Mi Max Pro 128GB

Found out also the problem causing the Bluetooth Address getting corrupted.

First I'm going to explain why it is getting corrupt. This is due to the Locked Bootloader flashing TWRP via MiFlash Beta.

The whole step was this:

First: I flashed the Official Global ROM from en.miui.com using the EDL Mode and MiFlash Beta to return to Stock ROM

Second: Boot up and checked the Bluetooth Address to see if it is okay. Bluetooth Address should be unique.

Third: I reboot to EDL Mode and flash the TWRP for Locked Bootloader via MiFlash Beta

Fourth: When you boot to Recovery Mode, it will ask you a password to decrypt the phone, it won't let you also mount anything and you can't also flash any flash file. You have to Format/Wipe the Data first and reboot to recovery again. This is the one causing the Bluetooth Address to get corrupt

Fifth: So after you wipe you will flash the Custom/Unofficial MIUI ROM you want.

Sixth: After you flash you will see the Bluetooth Address on About Device>Status get corrupted.

FIXING THE BLUETOOTH ADDRESS CORRUPT

We will be modding/combining the Official Fastboot ROM and the Custom/Unofficial Rom

First: Download a Fastboot ROM here : http://en.miui.com/a-234.html, choose your right Device.

Second: Download a Custom/Unofficial MIUI Rom like Xiaomi.eu/MultiROM/Miui.su/MiuiPro etc.

Third: Extract the Fastboot ROM, and Extract the Unofficial Rom

Fourth: Copy all the files from the Unofficial Rom/firmware-update/ folder, the boot.img and system.img to the Fastboot ROM/images/ folder, then overwrite all the files.

Fifth: Download a TWRP Recovery.img in https://twrp.me/Devices/ it's either Helium/Hydrogen, then copy this to the Fastboot ROM/images/ folder. then overwrite the recovery.img

Sixth: Boot to EDL Mode and tick the "clean all" on the lower right then flash the Modded Fastboot Rom

Seventh: Now try booting on your phone first and checked the Bluetooth Address, you'll get something like on the Third Screenshot.

Eight: Now copy the Unofficial Rom you want to your SDCard

Ninth: Boot up in the recovery and you will see that the TWRP won't ask your password to decrypt the phone, because it is already decrypted. Now wipe it all except the MicroSD, this include the system and internal sd.

Tenth: Flash the ROM you want. When you try rebooting it will say no OS found. Try rebooting it to Recovery and flash the Unofficial Rom again, then reboot.

Elevent: and voila. It's done. You will now have a working Bluetooth Address and you can also manually update if there's an update by flashing it via TWRP