Here is a solution for when BLE has a problem and you can update it compulsively. iOS only.
First, get nevo into DFU Mode.
How to get to DFU Mode.
1-"forget nevo" on nevo app-"my nevo", turn off the app.
2-take out watch battery CR2025, reinserting the battery while holding the 1st and 3rd button at the same time. This is important, you will see all the white LEDs flash, now nevo is in DFU Mode; if not, take out the battery and try agin.
Second, turn on the app, on the first interface "let's get started", long press the screen/the watch image, BLE update starts.