Thanks for your fast reply, but I find a better solution after search :).
In first, before try dirty flash Global over Beta, I read some threads where people said they succeed to dirty flash Global over Beta without problem, it's why I tried ^^.
After few search this evening, I found people...
I did a dirty flash for update to "xiaomi.eu_multi_MI5X_V188.8.131.52.ODBCNXM_v11-8.1" from " Xiaomi.eu Beta 9.10.10".
All work fine, except Mi Messaging application than crash when I try open it. I tried clear data but it change nothing.
There is a way to solve this problem without flash with...
Mi Band 4 NFC is only in Chinese and English, no more.
You can use a Modified Mi Fit Application to force your Mi Band 4 to be in English.
Modified Mi Fit - English - Mi Band 4
Envoyé de mon MI 5X en utilisant Tapatalk
1) Reboot to fastboot mode (press vol(+) and power) wait for vibration. (the screen is also black, don't worry about this).
2) On computer install previous firmware via fastboot: ( https://androidfilehost.com/?fid=11410963190603853188 )
3) Your phone will reboot and fixed.
Solution by @mbppereira.