About This File
Here NINEBOT APP ANDROID V3.5.1
This app worked fine, example for downgrade ninebot mini firmware v1.2.8 to v1.1.7, Some user meet last days issues for downgrade , maybe new app version v3.6 is guilty, because launch last 24 june, Please try with this app version
If not working fine for downgrade please take other previous version like 3.4.0 or 3.3.1....
Others previous Ninebot APK here (thank you John Eucist) http://www.apkmonk.com/app/cn.ninebot.ninebot/#previous