Issue solved ;). Reading help notes from app "Notify & Fitness" show me the light...
It's just need to connect some Bluetooth system to the phone (like headset or similar) in order to prevent Bluetooth disconnection.
Maybe you can add this to the Q&A or FAQ
Thanks again and have a nice day
Santi
Thank @MagicalUnicorn for explanation. Now I have a new problem :cry:. Looking the options for flash firmware, resources and fonts with "Notify & Fitness for Mi Band" , I clicked to flahs Fonts from official firmware and somethig wrong was happened because flashing stoped at 60%and show "Connect...
Thank you so much, I live in Spain and I've recived tow days ago my Mi Band 3 NFC. After pairing the band rest in chinese so not useful at all...
I flashed your custom firmware and now is in Spanish see atached file.
Only one question, blue colour on display is a hardware or software...