I updated my band 4 to version 1.0.9.20 (I currently have the FW 1.0.7.60) immediately when I finished the update, it appeared on my bracelet "connect to my fit to update", I had to use my fit (latest version of playstore 4.0. 15) to update (downgrade) to version 1.0.7.60. It's the 2nd time that happens to me, I don't know if it's because I make a big jump between firmware or the app I use is not useful (notifi & fitness for mi band (8.17.0))