I do not like to repeat myself. Please read carefully this thread and try to understand what the problem is: The band is visible to the phone and the MiFit app, but it cannot pair to it, thus no firmware update can be performed.
Try as much as you like to mod the firmware. It will NOT be loaded to the band if it is not paired to the MiFit app. Even if you have the correct auth key, you cannot pair the band. Only a compatible MiFit version that can be paired to the "faulty" firmware can fix the problem.
By the way, the newest version 5.2.0 is also not able to pair with the band.
P.S. Please count how many times I have used the word "pair". This is the problem, not the connection!
I have EXACTLY the same problem.
I also tried deactivating my device under the Mi Fit App, but when I tried to add the band again, it detects it but it just simply won't syncs with it.
I also tried to install the firmware via notify (with all the alternative methods), but I only get errors while trying to do it.
The odd thing is that Notify is detecting the band charge % (when it reaches 100%, I get a notification) and also Notify is detecting the steps, but the band is stuck at the "Connect to app to update again" screen.
I also tried syncing/updating the band with another phone, but I get the same results.
I cleared the bluetooth cache, uninstalled and reinstalled both Mi Fit and Notify apps, and even I factory restored my phone (Poco F3) and all those attempts end with the same results.
As you said,
the band is visible to the phone and apps, but cannot be paired.
If you find a way to fix this band, please please let me know, I'm also giving up, but I just don't want to spend more mone on something that can be fixed.
Let's hope this gets sorted out!
