Set following DNS server 54.36.62.97 on your Android Smartphone.
Download and install the next APK. Register, connect your bike and update MC & BMS.
If you have MC15, you can upgrade to MC17. Upgrade to 25km/h max.
If you have MC17, you can upgrade to MC19. Upgrade to 29km/h max.
If you have MC19, you can downgrade to MC17. Downgrade to 25km/h max.
ONLY WORK ON CHINA MODEL
Remember to delete DNS server once you have your Qicycle in desired version.