After downgrading, the projector will keep trying to OTA update to v3.2.1. Disable automatic updates in Developer Options to stop this.
: Make sure your Yaber Pro V7 is turned off. Connect it to a computer using a USB cable if required (check your user manual for specifics). Yaber Pro V7 Firmware Update
For devices without internet or failed OTA updates After downgrading, the projector will keep trying to