How to downgrade Mi Band 6 to the previous old firmware version
WARNING: this procedure is only for expert users. Doing something wrong may stop band connect with official app / phone
PREREQUISITES - IMPORTANT!
1) Ensure new firmware is fully installed correctly with official app (fw, res, font installed)
2) Ensure you know which account you have used to login with official app (where Mi Band 6 is currently paired)
If you don't know, unpair band, hard reset band (from band settings menu), reinstall official app and create a new account to pair band. Your official app account will be required later. If you don't know the correct account the entire procedure will fails and your band will stop working
3) Install Notify app, pair the Mi Band 6 ("Mi Fit installed" status) and ensure band is connected, then go on tools -> update firmware and choose the old version
5) Use Notify app to install the old firmware only (you should see "connect to update" on band at the end). Do not try install resources then.
6) Uninstall the official app (do not open it, and do not allow official app to force update the firmware again)
7) Install an old official app version and login using the same account. Suggestion: install apk from freemyband.com to get the authkey code too
Notice: by using the same account you will get the Mi Band 6 already paired. If you try use a different/wrong account, you will not be able get band working!
8) If old official app version doesn't complete the firmware update automatically, open Notify app again and complete the update by uploading the resources. Hint: press reconnect bluetooth button on main left menu if Notify is not connected after reinstalling official app.
9) It's done!
Choose if you want keep or remove it. Check this tutorial Official app removal